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SpaceX Vehicles and Missions => SpaceX BFR - Earth to Deep Space => Topic started by: Lumina on 10/11/2016 10:50 PM

Title: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/11/2016 10:50 PM
(This is a splinter topic from the IAC discussion thread which started with the below post:)
http://forum.nasaspaceflight.com/index.php?topic=41249.msg1597551#msg1597551

From what we have learned from IAC speech, we can probably safely assume that:

(a) ITS won't be carrying ready-made tuna can habitats to Mars (there is no pod-dropping)
(b) There is no need to carry ready-made habs (wedge, or any other shape) because the ITS itself can serve as a temporary hab on Mars
(c) Habitat components will be delivered flat-packed for assembly on Mars (like all other cargo)

These assumptions lead to the conclusion that the very first humans on Mars (on a long-stay mission) will be building habitats. Agree / disagree with this conclusion?

What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/12/2016 02:23 AM
Last year NASA ran a competition for habs called the '3-D Printed Habitat Challenge'. There was only $40K up for grabs but some interesting designs were put forwards. There is some background in the article NASA Awards Top Three Design Finalists in 3-D Printed Habitat Challenge (http://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/2015winners.html). It's probably worth a trawl through to grab ideas.

The winning design was the Mars Ice House (http://www.marsicehouse.com/), which is well worth a look.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/12/2016 04:00 AM
The ice-house idea is nonsense, sadly NASA seemed to have based the award on how much like of a modern architecture monstrosity it would be, note that this idea cooked up by just such an architectural firm.

A building made of ice would by necessity have walls and air at freezing temperatures inside at all times and that would raise the metabolic requirements of anyone living in it to two or three times the normal calorie intake because the body must generate so much more heat.  The interior air's moisture will freeze out as layer of frost on to the interior much like the frost in a refrigerator, ruining the 'view' and making the air extremely dry and uncomfortable.  This frost will need to be constantly scraped off or else it will just grow forever and fill the habitat.  The incredible mass of all this ice is likely to cause ground subsidence and cracking in the ice walls.  Dust accumulation on the exterior will likewise rapidly render the interior dark.

When NASA puts a stamp of approval on nonsense like this it encourages space-cadet type thinking in all kinds of other areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/12/2016 06:15 AM

Basically impossible to discuss without knowing the effect of partial gravity on human health.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/12/2016 06:52 AM
Basically impossible to discuss without knowing the effect of partial gravity on human health.

Another fundamental health issue linked to habitat design is space radiation. It might end up that long term Mars residents do best when living in pits dug into the regolith, or at least in trenches.
Title: Re: Envisioning Amazing Martian Habitats
Post by: pietro on 10/12/2016 07:38 AM
One thing is the habitat itself. Another is the interior. What if the 2-3 m3 travelling-rooms (like the Japanese capsule/tube hotels) could be removed at the end of the trip from the ITS and transferred to the new habitats? At least for the initial rounds this would make creating the sleeping spaces very easy (until bigger rooms can be provided) and efficient, would make the ITS lighter for the return leg, etc. They could be stacked (again, like in the capsule hotels, or like in The Fifth Element).

Edit:

There are some spectacular capsule hotel ideas around: https://www.google.com/search?q=capsule+hotel&tbm=isch

These could be made robust enough to connect to a central air recycling system, so that they could be used as temporary safehouses in case of a depressurization event.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 09:49 AM
The ice-house idea is nonsense, sadly NASA seemed to have based the award on how much like of a modern architecture monstrosity it would be, note that this idea cooked up by just such an architectural firm.

A building made of ice would by necessity have walls and air at freezing temperatures inside at all times and that would raise the metabolic requirements of anyone living in it to two or three times the normal calorie intake because the body must generate so much more heat.  The interior air's moisture will freeze out as layer of frost on to the interior much like the frost in a refrigerator, ruining the 'view' and making the air extremely dry and uncomfortable.  This frost will need to be constantly scraped off or else it will just grow forever and fill the habitat.  The incredible mass of all this ice is likely to cause ground subsidence and cracking in the ice walls.  Dust accumulation on the exterior will likewise rapidly render the interior dark.

When NASA puts a stamp of approval on nonsense like this it encourages space-cadet type thinking in all kinds of other areas.

Insulation like expanded polystyrene (Styrofoam) could be produced from local resources too, it's just chains of C and H and you will produce lots of both all the time. If you have energy, water and CO2 all kinds of plastics will be easier to synthesize than to bring them from Earth. Building structural components for pressure vessels from ice will be impossible though. Melting caves in a glacier not so much. You will have to have enough ice above and around you to counter 10t per square meter of pressure if you want to build with ice.

I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 10:37 AM
One thing is the habitat itself. Another is the interior. What if the 2-3 m3 travelling-rooms (like the Japanese capsule/tube hotels) could be removed at the end of the trip from the ITS and transferred to the new habitats? At least for the initial rounds this would make creating the sleeping spaces very easy (until bigger rooms can be provided) and efficient, would make the ITS lighter for the return leg, etc. They could be stacked (again, like in the capsule hotels, or like in The Fifth Element).

Edit:

There are some spectacular capsule hotel ideas around: https://www.google.com/search?q=capsule+hotel&tbm=isch

These could be made robust enough to connect to a central air recycling system, so that they could be used as temporary safehouses in case of a depressurization event.

A room is not a pressure vessel. To judge how such a room would look (and how complex it would be and what mass it would require), look at ISS modules. Apart from some differences with thermal management it's pretty much the same challenge. Things don't are easier on Mars than they are in LEO just because it is a planet.

Only if you use local resources you don't have in space things may be easier than there. If you don't do that your Mars base will look very similar to the ISS, just sitting on the ground on Mars.

Title: Re: Envisioning Amazing Martian Habitats
Post by: redliox on 10/12/2016 10:39 AM
I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.

Well inevitably the first habitats on Mars will be Earth-made, but I refer to the first landings and the first teams to explore but then get down to the serious construction.  Once you have the equipment to shove regolith around and hopefully funnel it into 3D printing machines things open up.  The initial tin cans and inflatable tents might handle on the order of 3-10 people, whereas an actual city must house hundreds and eventually thousands onward.

My guess for the overall design of say a medium-sized settlement (or a very large base camp) with ~200 people would be the following:
1) Roomy but claustrophobic living space; no windows lots of dirt covering a 3D built structure.
2) Numerous garden areas, possibly domes, but primarily for plants to take advantage of natural sunlight.
3) Handful of metal nodes, such as airlocks or power systems, peaking out; mainly delivered from Earth but slowly becoming Martian-built.
In short, there would be lots of squat, building-sized mounds with greenhouses.

They would be this way because the safest landing sites probably will be in flat, boring areas with little else but the materials to build structures from.  No caves, lava tubes, or cliffs...just you, your machinery, and the dirt.  Hence why we might see slightly-boring-looking mounds for buildings on Mars...at least until you get a large enough population that starts barking for window space, then it may get more exotic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TheTraveller on 10/12/2016 10:39 AM
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 11:20 AM
Well the thing about ice houses is that you are going to get large hollowed out glaciers as a result of h20 mining. So the caverns will be there whether you decide to habitat them or not.

So it really comes down to what is the most efficient in automation and equipment to convert glacier to liquid water. It might be long bore holes or it could be large caverns. One of them provides instant buildable structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:34 AM
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:50 AM
I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.

Well inevitably the first habitats on Mars will be Earth-made, but I refer to the first landings and the first teams to explore but then get down to the serious construction.  Once you have the equipment to shove regolith around and hopefully funnel it into 3D printing machines things open up.  The initial tin cans and inflatable tents might handle on the order of 3-10 people, whereas an actual city must house hundreds and eventually thousands onward.

My guess for the overall design of say a medium-sized settlement (or a very large base camp) with ~200 people would be the following:
1) Roomy but claustrophobic living space; no windows lots of dirt covering a 3D built structure.
2) Numerous garden areas, possibly domes, but primarily for plants to take advantage of natural sunlight.
3) Handful of metal nodes, such as airlocks or power systems, peaking out; mainly delivered from Earth but slowly becoming Martian-built.
In short, there would be lots of squat, building-sized mounds with greenhouses.

They would be this way because the safest landing sites probably will be in flat, boring areas with little else but the materials to build structures from.  No caves, lava tubes, or cliffs...just you, your machinery, and the dirt.  Hence why we might see slightly-boring-looking mounds for buildings on Mars...at least until you get a large enough population that starts barking for window space, then it may get more exotic.
The best would be a very boring site right next to a nice water cliff.  Always easier to have gravity on your side, and bringing down a cliff is easier than digging a hole.
Fortunately, there seems to be quite a few glaciers at interesting latitudes on Mars.  These glaciers may be the equivalent of river junctions on Earth; rare but that's where all the cities are/ will be.
After all, you just need a single adequate emplacement.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:55 AM
There probably already is a thread about lava tubes, somewhere on the site?
Anyone have a link?  That could be amazing and spectacular.
Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 10/12/2016 11:56 AM
Well, a naturally occurring fibre available on Mars would likely be the mineral asbestos. Once you have located a deposit you have to crush it to liberate the fibres. Great stuff, non flammable, great insulator for heat sources etc, but of course the carcinogenic properties when inhaled pretty much rule it out. :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 12:19 PM
There probably already is a thread about lava tubes, somewhere on the site?
Anyone have a link?  That could be amazing and spectacular.

Lava tubes would be great, but you'd need to find one near water. The places with water (as pure as possible and as much as possible) is where you have to go to, there's no way around that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 12:35 PM
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 01:38 PM
Method only works at high altitudes on Mars.
ot be the safest place to live.

The Hellas glacier I thought was very low altitude and about 30-40 deg latitude.
It sounds like a great place for lots of water.
Great sun for power.
Low altitude for plenty of atmosphere.

Was also where they did the study to indicate glaciers under modest dirt overlay.

https://en.wikipedia.org/wiki/Hellas_quadrangle
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 01:58 PM
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 02:06 PM
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...

Well at least they could be below zero storage and play and refuge from radiation areas.
Also as mentioned above they should be able to be pressurized and provide a play area.
But above zero temperatures does provide problems.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 02:43 PM
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...

You can dump a lot of heat into ice that is at -50C without melting it. Well, I'm still at the glacier idea and not at ice domes of course... If you have enough water, you can even use sublimation cooling as the Apollo suits used on the Moon. And what you need to cool is not the house, but either the air in it or the equipment and all of this will necessarily be above the freezing point of water. The ice will need to be insulated anyway.

And whatever you do, thermal management will be a thing you have to care for, but this much easier on Mars than in space where you can only radiate heat away or evaporate water (which you will have only a very limited supply of).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 03:26 PM
I find this thread would be more fun and Amazing if we thought and planed for the larger scale installations required for 1 million colonists.

We could skip the first 20 years, that are probably going to be systems that are prefabricated and come from Earth, and think about the longer term, large scale infrastructures?

-Can you fit one million people and their food production systems in a glacier?  How long will the heat sink last?
-How far away can resources be?
-What is the energy required?
-How large will the spaceport be?
-What will be the ground level infrastructures?
-What is a good size for a community in the Mars environment?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/12/2016 04:44 PM
It really depends on where on Mars the base is and what the local resources and circumstances are.

For Hellas basin glaciers covered in a few meters of Regolith, assuming it's a relatively pure water ice glacier, maybe designs that consume the ice of the glacier, taking advantage of the thicker atmosphere in the Hellas basin. As the ice is consumed for ISRU propellant, oxygen and water, the void created might be living space. The regolith cap might be held in place both by mixing with water and freezing it and building support structure.

There's room for very large underground spaces to be hollowed out since the glaciers are hundreds of meters thick and cover square kilometers. The roof over the space would be controlled architecture using regolith rather than depending on something like lava tubes natural roof. Since the roof is designed it could be strong enough to support suspended structures hanging from it.

The space would grow as a side effect of consuming the ice anyway so the main design decision would be what shape to make the cavity.

I picture a growing vertical space that gets to be over 300m deep before hitting rock. There might be a truss structure on the surface to allow suspending structures in the space. Eventually you could have a huge 3D space with structures coming up from the floor, suspended from the roof and built into the rock walls of the cavity.

At Mars gravity with sea level air pressure flight is very easy so a main mode of transport in the space is flying. There are light airy buildings with 100 levels and lots of open balconies (that people can fly to) looking out on a vast 3D cityscape. Lower gravity, suspension from the roof and materials like carbon fiber allow pretty amazing architectural expression not seen on earth. You take an elevator to the floor which is parklike and includes lakes or the Mars surface above which is mostly industrial and utilitarian.

No idea how stable the glacier is or how much it flows. I'm assuming there's a site where there's a buried Glacier that's pretty static by earth standards. The low gravity and lack of new snowfall ought to promote stability.

I think any civilization on Mars depends on plentiful energy. Hellas is near the equator so good for solar. I think nuclear is needed anyway.

I think the best middle term chance at building pleasant environments on Mars is with large open underground spaces that permit O'Neill colony like landscapes with trees and open water. Building within the voids creating by mining glaciers in Hellas might permit this with decent intermediate designs, in a space that's being created anyway and a location that has many advantages.

If residents like the idea of natural sunlight, it can be collected on the surface and piped in. The roof isn't very thick and it's not difficult. The roof is sufficient though to protect against radiation.

A single glacier in the Hellas basin could easily hold a city of million people in this mode. At some point it would start piping in water from other nearby glaciers and starting suburbs.

I'm assuming that agriculture is just another industrial activity and is done in completely controlled environments with artificial light and works just as well in vertical stacks 300 meters high underground as anywhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 05:58 PM
I find this thread would be more fun and Amazing if we thought and planed for the larger scale installations required for 1 million colonists.

We could skip the first 20 years, that are probably going to be systems that are prefabricated and come from Earth, and think about the longer term, large scale infrastructures?

-Can you fit one million people and their food production systems in a glacier?  How long will the heat sink last?
-How far away can resources be?
-What is the energy required?
-How large will the spaceport be?
-What will be the ground level infrastructures?
-What is a good size for a community in the Mars environment?

I think a million people would require at some point digging into rock, since you will need the water for other things. It would probably be a good idea to start at a place where you can spread out to other glaciers at least for producing fuel.

Energy will be tight, nuclear power would be necessary at least to buffer solar power problems from global sand storms that you'll be guaranteed to run into at some point. You solar power farms probably would be big enough to be seen from orbit ;-)

Going underground (either ice or rock) in the long run is inevitable, not only for radiation shielding but also for protection against landing and launching (and sooner or later crashing) spacecraft. I would expect very little ground-level infrastructure. Transportation may work for water (you will need thousands of tons to fuel a single ship), maybe buried and insulated pipelines. You could put some distance between your spaceport and ISRU facilities and the actual city, although transporting people and cargo over ground would be a major PITA. Expect many tunnels. Prospecting for iron for heavy machinery would have quite high priority I guess.

Managing your thermal and energy budgets wisely would be crucial, especially as both depend on each other: Any heat you have to reject by basically heating the ground, air or sky (by radiating it away) is wasted energy. Trying to do things as efficient as possible would be much more important than down here on Earth. I'm sure though that this would be easier with a million people than with a dozen (relatively, not absolutely).

You'd probably wise to simulate things beforehand, so you don't realize you've started it wrong too late...

At a million people population density would be high or you would need to spread out very far.

In situ research to find the best place before even starting is important. Even the first crews though have to start out where the water is or they and their ship will never make it back.

All of this would be a major undertaking, the biggest in the history of mankind. And building the spacecrafts would be just the feeble beginnings.

But even now you will find that people roughly fall into two groups: The first says "Why? I just want to sit on my couch, leave me alone, you're crazy!" and the second says "Hey, let's start! What do I have to do?". But I think anyway that not having anything to do is the curse of modernity...
Title: Re: Envisioning Amazing Martian Habitats
Post by: b0objunior on 10/12/2016 06:20 PM
It really depends on where on Mars the base is and what the local resources and circumstances are.

For Hellas basin glaciers covered in a few meters of Regolith, assuming it's a relatively pure water ice glacier, maybe designs that consume the ice of the glacier, taking advantage of the thicker atmosphere in the Hellas basin. As the ice is consumed for ISRU propellant, oxygen and water, the void created might be living space. The regolith cap might be held in place both by mixing with water and freezing it and building support structure.

There's room for very large underground spaces to be hollowed out since the glaciers are hundreds of meters thick and cover square kilometers. The roof over the space would be controlled architecture using regolith rather than depending on something like lava tubes natural roof. Since the roof is designed it could be strong enough to support suspended structures hanging from it.

The space would grow as a side effect of consuming the ice anyway so the main design decision would be what shape to make the cavity.

I picture a growing vertical space that gets to be over 300m deep before hitting rock. There might be a truss structure on the surface to allow suspending structures in the space. Eventually you could have a huge 3D space with structures coming up from the floor, suspended from the roof and built into the rock walls of the cavity.

At Mars gravity with sea level air pressure flight is very easy so a main mode of transport in the space is flying. There are light airy buildings with 100 levels and lots of open balconies (that people can fly to) looking out on a vast 3D cityscape. Lower gravity, suspension from the roof and materials like carbon fiber allow pretty amazing architectural expression not seen on earth. You take an elevator to the floor which is parklike and includes lakes or the Mars surface above which is mostly industrial and utilitarian.

No idea how stable the glacier is or how much it flows. I'm assuming there's a site where there's a buried Glacier that's pretty static by earth standards. The low gravity and lack of new snowfall ought to promote stability.

I think any civilization on Mars depends on plentiful energy. Hellas is near the equator so good for solar. I think nuclear is needed anyway.

I think the best middle term chance at building pleasant environments on Mars is with large open underground spaces that permit O'Neill colony like landscapes with trees and open water. Building within the voids creating by mining glaciers in Hellas might permit this with decent intermediate designs, in a space that's being created anyway and a location that has many advantages.

If residents like the idea of natural sunlight, it can be collected on the surface and piped in. The roof isn't very thick and it's not difficult. The roof is sufficient though to protect against radiation.

A single glacier in the Hellas basin could easily hold a city of million people in this mode. At some point it would start piping in water from other nearby glaciers and starting suburbs.

I'm assuming that agriculture is just another industrial activity and is done in completely controlled environments with artificial light and works just as well in vertical stacks 300 meters high underground as anywhere.
There's a third group of people, the ones that think Mars is not the solution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RoboGoofers on 10/12/2016 06:32 PM
Somewhat jokingly: what common things would have to be reevaluated considering Mars Gravity? Earth stairs would probably be awkward. Sinks would have to be wider or deeper to catch splashing water. Walking with a cup full of water might be messy as it sloshes over the brim.

It might be impossible to assume what will work beforehand, and a comfortable solution will only be found after people get there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 08:08 PM
There's a third group of people, the ones that think Mars is not the solution.

Of course Mars isn't a solution. Mars is an interesting problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/12/2016 08:32 PM
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/12/2016 09:17 PM
I don't think there is any problems with the low temperatures on the 'shed' part of the ice house. The conditions inside that part are much better than outside. You have

* Pressure, enough not to need a pressure suit
* Breathable atmosphere
* Protection from radiation

It gives a usable space for very little landed mass.

Inside that space you have a second chamber, lets call it a 'conservatory', which is insulated with aerogel on the inner surface of the ice so to can be warmed to 20C. This be used to grow plants and as space to hang out.

Inside that you have the landed aluminium hab with all the ECLSS etc.

Unless there is some big flaw that I'm missing it seems you get a much bigger hab for very little extra landed mass.


Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 09:38 PM
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

Nobody is saying that habitats in ice would need to be cold. Insulating walls really isn't rocket science, even your deep freezer manages this. My house has snow on the roof in the winter without being cold inside. Polyethylene can be synthesized from hydrogen and carbon, you wouldn't even have to bring it.

Building big pressure vessels is HARD. Really. Drilling into rock or melting into ice gives you the big advantage of not having to build pressure vessels because you have all the weight of the ice or rock on top to counter the pressure. This weight comes for free, it's already there.

And with "pressure" I mean 10 tons for every square meter of your arcade trying to rip it apart from the inside. The tension the walls have to keep up against goes up proportionally with the radius of the vessel. Plastic just isn't going to work, you'll need aluminum or steel or carbon fibre, and lots of it. And you will have to build it as a sphere or a cylinder, because it will pop out immediately otherwise. And the smallest weakness somewhere can make it fail catastrophically.

And you will still have to insulate it, because the regolith on top and beneath and with it the skin of your building will be at the same temperature as the ice in a glacier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: renclod on 10/12/2016 09:49 PM
Most people crazy enough to leave Earth for Mars will treasure mobility above all else, probably. They will hate to be pinned down for long whiles. They will work on building large rovers and then move to another site.  They will build robots, start them on a site task and then move on.  Airlocks will be plenty and large mobile habs likewise, probably. For a century at least.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/13/2016 12:20 AM
(Reposting from general discussion thread)

Here's my vision for amazing habitats on Mars. I imagine networks of cliffside cities with many panoramic windows dug out from mesas, natural canyon walls or even Tatooine-style dugouts, featuring:
 
- multiple levels,
- dozens of windows and dome-covered verandas with panoramic views,
- excellent protection from radiation,
- robustly stable indoor temperatures, so one less thing that can go wrong,
- shirtsleeve access via tunnels to surface facilities above or nearby (e.g. power generation, greenhouses, landing pads),
- redundant protection from decompression with segments protected by automatic airlocks,
- grand and inspiring elaborate carved entrances with inspiration from all ancient cultures on Earth,
- direct shirtsleeve access (via tunnels / airlocks) to mines for resource extraction

Besides excavation equipment and the usual internal equipment needed for habitats, the following will be needed:

- a scalable and flexible solution for a flooring and false ceiling system that can eventually use in situ resources,
- a scalable solution for sealing excavated tunnel surfaces that can also eventually use in situ resources (some kind of epoxy?),
- automatic airlocks and door systems to separate segments for safety,
- a modular system to create windows or external domes to cover "verandas", also evolvable to use in situ resources for the future.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:23 AM
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

I agree with most of your critique of the ice house. None of those things apply to occupying space inside a glacier. You need to insulate the ice face, but there's no reason the temperature in the space opened up inside the glacier can't be like Hawaii. If you start at the edge where the glacier meets rock and expose it as you consume the ice going down, you can build into the rock or attach to it as well as suspend structures from the roof.

I don't think any sort of surface structure can provide a pleasant or safe city environment on Mars. That requires very large open spaces with normal atmosphere and as you suggest pleasant temperatures. It all has to be shielded from surface conditions and permit construction in an earthlike "outdoor" environment.

If you build anything on the surface it has to be a separate pressure vessel. It's just incredibly wasteful of materials and effort to build tiny volumes of habitable space on the surface when you are creating a huge habitable volume that can be very efficiently pressurized as a side effect of consuming the glacier anyway. The image of ice near you suggests cold but there's no real issue with the void in the glacier being cold. The ice face just has to be insulated to protect it from the waste heat of the settlement. Unlike the icehouse design nothing is built out of ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:30 AM
Inside that space you have a second chamber, lets call it a 'conservatory', which is insulated with aerogel on the inner surface of the ice so to can be warmed to 20C. This be used to grow plants and as space to hang out.

Growing plants inside that ice house would require tremendous energy for lighting. It would be very hard to keep temperatures low enough to not melt the ice dome. Not impossible but for greenhouses I think there would be better solutions. The plants don't need radiaton protection.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:32 AM
(Reposting from general discussion thread)

Here's my vision for amazing habitats on Mars. I imagine networks of cliffside cities with many panoramic windows dug out from mesas, natural canyon walls or even Tatooine-style dugouts, featuring:
 
- multiple levels,
- dozens of windows and dome-covered verandas with panoramic views,
- excellent protection from radiation,
- robustly stable indoor temperatures, so one less thing that can go wrong,
- shirtsleeve access via tunnels to surface facilities above or nearby (e.g. power generation, greenhouses, landing pads),
- redundant protection from decompression with segments protected by automatic airlocks,
- grand and inspiring elaborate carved entrances with inspiration from all ancient cultures on Earth,
- direct shirtsleeve access (via tunnels / airlocks) to mines for resource extraction

Besides excavation equipment and the usual internal equipment needed for habitats, the following will be needed:

- a scalable and flexible solution for a flooring and false ceiling system that can eventually use in situ resources,
- a scalable solution for sealing excavated tunnel surfaces that can also eventually use in situ resources (some kind of epoxy?),
- automatic airlocks and door systems to separate segments for safety,
- a modular system to create windows or external domes to cover "verandas", also evolvable to use in situ resources for the future.

If you start at the edge of the glacier where it meets rock and expose the rock face as you consume the glacier you can attach to or build into the rock as well as suspend structures from the roof. The process of using the ice opens up space for this sort of thing in a volume that can have a comfortable atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:33 AM
Moving my post from the IAC thread here.

Glaciers may move on Mars but sure at a much slower rate. The ice is much colder and harder. Also forces moving them are smaller. On earth glaciers move because they are on a slope or because there is new precipitation which produces thrust. Both would be absent or much smaller on Mars.

Habitats could be well insulated houses. The caves in the glacier could be very large so heat from the habitats can dissipate into the glacier without causing melting. The caves would be pressurized so people could be outside without spacesuit though they would need heavy arctic clothing. If temperatures could be kept at -10-15C and the air dry, being outside could be even fun with little air movement. This would likely not be the only type of habitat but it could be one option.

I have visited a salt mine with huge caves. That should look somewhat similar and it was gorgeous.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:46 AM
Another concept that could give wide open spaces though with columns.

Place columns made of Marscrete, reenforced with basalt fibre and space them equally in a hexagonal pattern. Build prefab hexagonal domes to place them on top of the columns. Place a regolith cover on top of the domes heavy enough to counteract pressurization. That's heavy and the columns need to be strong enough to support them. The structure should be strong enough to stand up when one column fails and needs to be replaced. That pattern can be extended gradually.

The structure would need safety features in case of breaches. It should have sections that can be sealed off. They should also have small pressurized shelters and maintain pressure when breached long enough for people to reach those shelters.

The advantage would be a large connected area where people can roam without pressure suits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:58 AM
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

Nobody is saying that habitats in ice would need to be cold. Insulating walls really isn't rocket science, even your deep freezer manages this. My house has snow on the roof in the winter without being cold inside. Polyethylene can be synthesized from hydrogen and carbon, you wouldn't even have to bring it.

Building big pressure vessels is HARD. Really. Drilling into rock or melting into ice gives you the big advantage of not having to build pressure vessels because you have all the weight of the ice or rock on top to counter the pressure. This weight comes for free, it's already there.

And with "pressure" I mean 10 tons for every square meter of your arcade trying to rip it apart from the inside. The tension the walls have to keep up against goes up proportionally with the radius of the vessel. Plastic just isn't going to work, you'll need aluminum or steel or carbon fibre, and lots of it. And you will have to build it as a sphere or a cylinder, because it will pop out immediately otherwise. And the smallest weakness somewhere can make it fail catastrophically.

And you will still have to insulate it, because the regolith on top and beneath and with it the skin of your building will be at the same temperature as the ice in a glacier.

...and any "buildings" you build on the surface have these issues that have to be addressed for each structure separately. Each ends up enclosing a tiny habitable volume at great expense. Meanwhile you have to consume vast amounts of ice in the glacier just for propellant and basics leaving a huge and growing volume that's comparatively cheap and easy to pressurize and make comfortable. That space is a resource unique to this sort of location.




Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 07:11 AM
Moving my post from the IAC thread here.

Glaciers may move on Mars but sure at a much slower rate. The ice is much colder and harder. Also forces moving them are smaller. On earth glaciers move because they are on a slope or because there is new precipitation which produces thrust. Both would be absent or much smaller on Mars.

Habitats could be well insulated houses. The caves in the glacier could be very large so heat from the habitats can dissipate into the glacier without causing melting. The caves would be pressurized so people could be outside without spacesuit though they would need heavy arctic clothing. If temperatures could be kept at -10-15C and the air dry, being outside could be even fun with little air movement. This would likely not be the only type of habitat but it could be one option.

I have visited a salt mine with huge caves. That should look somewhat similar and it was gorgeous.

This is what I was assuming about glaciers there. Without new snowfall or geological activity I'd think they'd be much slower (though it's clear from the pictures that they flow, it may not be on a human relevant timescale). I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 07:31 AM

 I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.

Keeping the habitats warm is not what I am concerned about. Dumping waste heat while making sure the ice won't melt is the engineering challenge IMO. That would require the ice surface to be exposed and temperatures well below freezing. People do enjoy winter temperatures and snow and ice. Though some caves may be isolated and kept warm so plants can grow.

Technical solutions to dissipate low temperature heat energy would be complex and may be prone to failure. Better to have a naturally stable system.

Having some green to walk throug is nice to have. But light for plants would introduce a lot of heat that needs to be dissipated. I am not thinking of growing much food there but plants that need little light as a public park. Plants like ferns and philodendron. Plus a few separately lighted spots for plants that grow fruit like strawberries.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 09:36 AM

 I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.

Keeping the habitats warm is not what I am concerned about. Dumping waste heat while making sure the ice won't melt is the engineering challenge IMO. That would require the ice surface to be exposed and temperatures well below freezing. People do enjoy winter temperatures and snow and ice. Though some caves may be isolated and kept warm so plants can grow.

Technical solutions to dissipate low temperature heat energy would be complex and may be prone to failure. Better to have a naturally stable system.

Having some green to walk throug is nice to have. But light for plants would introduce a lot of heat that needs to be dissipated. I am not thinking of growing much food there but plants that need little light as a public park. Plants like ferns and philodendron. Plus a few separately lighted spots for plants that grow fruit like strawberries.

If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.

In fact the ISS with its 450 tons of pressure vessels, structure, airlocks, solar panels, heat exchangers etc. for 6 people is very similar to what you would need to land on Mars for a similar habitat on the surface. Transporting pressure vessels to Mars or building them on Mars just doesn't scale and the fact that you DO have solid material like ice or rock where you can carve out your habitats is a major resource on Mars compared to empty space. And once you have set up your machinery for cutting through ice or rock you can expand for a long time.

And of course at some point you would need to grow plants (and maybe fish) for food. Either that or have all your food imported from Earth forever.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 10:13 AM
If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.


Yes, of course it will need heating. But with energy consumption inside the living quarters and good isolation not much.

What I mean with naturally stable is the heat flow from habitat to ice being in a range where you don't need technical intervention to keep the temperature outside the habitat and within the ice cave in a practical range. As that cave would have pressure and breathable atmosphere you can vent excess heat by opening the window like you do on earth. Just size habitat size and total energy consumption and size of the ice cave so you don't need active cooling for the cave.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 11:08 AM
If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.


Yes, of course it will need heating. But with energy consumption inside the living quarters and good isolation not much.

What I mean with naturally stable is the heat flow from habitat to ice being in a range where you don't need technical intervention to keep the temperature outside the habitat and within the ice cave in a practical range. As that cave would have pressure and breathable atmosphere you can vent excess heat by opening the window like you do on earth. Just size habitat size and total energy consumption and size of the ice cave so you don't need active cooling for the cave.


Yes, over all of your habitat this should be the goal, since heat you have to remove is wasted energy. But your habitat will not be just one big cave, it will have lots of rooms and tunnels and water tanks and whatever, with some parts (storage, living quarters) only generating little heat and others (machinery, greenhouses) generating a lot, so you will have to have loops of water pipes to move the heat around from places where's too much of it (cooling them) to other places where's too little of it (heating them).

In the ideal case all of this cancels out, but I guess it will be very, very hard to plan this. Total energy consumption will not be static anyway. So you will have to have the capability to dump heat somewhere to get rid of it and also to generate heat at times where you don't generate enough.

Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/13/2016 11:24 AM
So a roof of 27m thick clear ice would be self supported with 1 atm pressure inside. The roof would let natural light in. Of course if you had an air leak the roof would collapse. Is there any plants that grow at -10C?

EDIT:
Possibly little green houses so the plants can be kept warm. Up here in new hampshire they do little crop row greenhouses about 4 feet wide and 3 feet high. Just enough to keep plants warm in the winter.

Probably gone to need some sort of air conditioner to make sure excess heat doesn't melt the glacier. But air conditioning is easy...
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 11:58 AM
Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.

The whole cave would be pressurized. And soon, if not immediately, filled with breathable air. There will be plenty of it available from fuel ISRU. Oxygen because the engines run fuel rich and the production is stochiometric. Nitrogen or a breathable mix of oxygen and argon are just a byproduct of extracting the CO2 for the Sabatier process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RoboGoofers on 10/13/2016 04:31 PM
What about waste products from ISRU? Isn't there a lot of salt in the water on mars? What about salt bricks? If you are going to be generating waste products, you might as well find a use for them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 10/13/2016 04:51 PM
Salt is an important material to have. Using it as a building material would be a huge waste. Any salt gathered through ISRU "waste" should be stockpiled for later use.

From Wikipedia https://en.wikipedia.org/wiki/Salt :
Quote
Its major industrial products are caustic soda and chlorine, and is used in many industrial processes including the manufacture of polyvinyl chloride, plastics, paper pulp and many other products. Of the annual global production of around two hundred million tonnes of salt, only about 6% is used for human consumption.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 09:43 PM
Let's see how much salt would be in a large body of water. If it is from precipitation, virtually none. If it is an ancient ocean it may be more. But the oceans of earth have accumulated their salt content over billions of years from rivers. The liquid oceans of Mars did not exist that long at all. I expect that it would still even pass as drinking water, except for possible poisonous ingredients.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/13/2016 10:04 PM
Let's see how much salt would be in a large body of water. If it is from precipitation, virtually none. If it is an ancient ocean it may be more. But the oceans of earth have accumulated their salt content over billions of years from rivers. The liquid oceans of Mars did not exist that long at all. I expect that it would still even pass as drinking water, except for possible poisonous ingredients.
Don't know about salt, but the water on Mars is 5 times more enriched in deuterium than Earth water, probably through loss of hydrogen in the upper atmosphere.  Venus water has 200 times the concentration of Earth.  Water was probably liquid on Mars for quite some time, so quite a bit of leaching should have taken place, followed by evaporation.
I expect there might me very salty plains, where the water evaporated rather than froze?

Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 11:03 PM
Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.

The whole cave would be pressurized. And soon, if not immediately, filled with breathable air. There will be plenty of it available from fuel ISRU. Oxygen because the engines run fuel rich and the production is stochiometric. Nitrogen or a breathable mix of oxygen and argon are just a byproduct of extracting the CO2 for the Sabatier process.

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

One thing about living on Mars will be that wasting anything will be a bad thing. You'll be fighting an uphill battle against entropy all the time. Finding ways to manage things with minimal losses will be paramount.

(Actually this will be a good thing. Finding ways to deal with all this as a matter of fact on Mars will mean that you will be able to use all of this on Earth to, living without actually wasting things and destroying the eco-systems. The Martians will teach the Earthlings lessons they need to learn anyway.)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/14/2016 04:13 AM
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/14/2016 09:26 AM
Leaving aside the Zygote-style caves inside ice sheets for the moment:

Which concept would take less total labor and energy to construct for equivalent pressurized volume and level of radiation protection?

1. carving a cave out of a cliffside at a location chosen for the ideal rock properties for carving, or
2. building "temple structures" consisting of columns and arches on a flat plain and covering them with regolith.



Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 10:20 AM

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

It seems we have a misunderstanding. I am not suggesting wasting anything. We have a large habitat with breathable air. We have a house that is not pressurized by itself because it does not need to be. Opening the window exchanges air with the larger cave which is closed. Nothing is wasted unless you see pressurizing a large cave with breathable air is waste.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 10:37 AM
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.

I think you're confusing pressure vessels with making things gas-tight. "Arches, vaults, columns and other compression load bearing structures" won't help at all because your building will not be under compression at all. It will be under tension. The atmospheric pressure inside will try to push things apart form the inside.

Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

Cracks in rock in a cave or tunnel aren't a problem, a thin membrane to prevent gas from escaping is easy, but there is no such thing like a "thin membrane pressure vessel". In a cave the pressure would be countered by the weight of the rock above and around it. If you don't have that weight you have to counter the pressure by tension in your pressure vessel and this not going to be a thin membrane then or bricks, or anything short of steel or aluminum, or massive reinforced concrete.

And yes, you need more than just pressure vessels to live in, but they're the biggest things you need and if they fail you won't have any time to fix things, because you will be dead immediately. They are the first and most crucial thing you need. And if you want to live and grow food in them, they need to be big and you need many of them and they need to be safe.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/14/2016 10:54 AM
Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

1.5g/cm^3 means 1.5t/m^3. So more like 6.67m thick for 10t. Mars gravity is only 0.38g, so more like 17.54m. Maybe it would make sense to reduce the pressure in the hab.

For a bigger habitat the excavated regolith for the cover will be smaller relative to the total excavated regolith. So I think bigger (or better deeper) is better. In theory.

Edit: Ups, corrected.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 11:58 AM

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

It seems we have a misunderstanding. I am not suggesting wasting anything. We have a large habitat with breathable air. We have a house that is not pressurized by itself because it does not need to be. Opening the window exchanges air with the larger cave which is closed. Nothing is wasted unless you see pressurizing a large cave with breathable air is waste.

OK, so a big buffer of pressurized volume to dump excess heat into. I would guess just dumping into a more remote part of the glacier with water loops and heating the ice there a bit would be easier, but on the other hand you will be carving out bigger and bigger caves all the time anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/14/2016 12:38 PM
There are clear advantages to having enormous spaces. A not-so-obvious advantage is that all other things being equal, the greater the enclosed volume, the slower the rate of change in the proportions of the gases in the (well mixed) breathable air out of any given source of imbalance, giving more time for the ECLS systems to respond and correct that O2/CO2 imbalance. Having more time to react is generally a good thing in closed loop control systems. Every contribution to robustness adds up and after some point where every subsystem is made robust with relaxed tolerances you can have a habitat design that can be surprisingly safe. That would be the way to go, I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 01:08 PM
OK, so a big buffer of pressurized volume to dump excess heat into. I would guess just dumping into a more remote part of the glacier with water loops and heating the ice there a bit would be easier, but on the other hand you will be carving out bigger and bigger caves all the time anyway.

That's the idea. As I said this should be designed to get rid of excess heat without requiring any active technical devices. Plus the children can go outside and play. -15C and dry air are ok without much wind. You could make snow, too. :)

There are glaciers big enough that you could build a whole 1 million people city that way and not use much of its volume. Though I believe this would be only one of different types of habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/14/2016 01:25 PM
Open pit mining techniques could be used to excavate large canals (100m+ deep). The pressurized "membrane" would be covered with 20m regolith from both sides.

The result could resemble Ceres station in Expanse.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 01:55 PM
Yea I loved the comment about the martians teaching us earth people how to take care of our resources. Just like in expanse!
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 02:07 PM
Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

1.5g/cm^3 means 1.5t/m^3. So more like 6.67m thick for 10t. Mars gravity is only 0.38g, so more like 17.54m. Maybe it would make sense to reduce the pressure in the hab.

For a bigger habitat the excavated regolith for the cover will be smaller relative to the total excavated regolith. So I think bigger (or better deeper) is better. In theory.

Edit: Ups, corrected.

Yeah, I'm just using 1/3 g as Mars gravity for napkin engineering.

You can reduce hab-pressure slightly, but not by much. Or you will have to go up with the oxygen ratio, which comes with its own problems. There are good reasons for staying at Earth-like atmospheric pressure (like on the ISS).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 10/14/2016 02:50 PM
If you are trying to melt ice for its water, (and to make a habitat bigger) one advantage of an ice habitat is that any waste heat can be used for that very thing, melting ice in new areas. You just have to find a very efficient way of moving the heat to where you need it.

I'm not sold on this idea but I did want to point that out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/14/2016 03:38 PM
On one side is a rock wall sculpted with broad terraces and balconies connected to habitations extending a thousand feet up to the distant roof. It looks out into a space extending kilometers that is so vast it seems like an outdoor landscape. The floor is parkland that includes forrests and lakes. Towers as tall as 100 stories with broad balconies that offer landings for flying cars rise in the foreground. Some structures hover in mid air suspended from the roof. Architecture is fanciful and creative, liberated from earthly constraints of weather, geological instability and high gravity. Flying cars, safe because they're autonomous, are much more efficient than on earth. In the distance at night is a panorama of lights embedded in the ice face as an art project, seeming like an arc of starry night sky.

Unlike an O'Neill space colony, it grows organically in place, inhabited the entire time. It didn't have to be planned in every detail and completed before it was habitable. It's a more ordinary city in that respect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: b0objunior on 10/14/2016 03:48 PM
On one side is a rock wall sculpted with broad terraces and balconies connected to habitations extending a thousand feet up to the distant roof. It looks out into a space extending kilometers that is so vast it seems like an outdoor landscape. The floor is parkland that includes forrests and lakes. Towers as tall as 100 stories with broad balconies that offer landings for flying cars rise in the foreground. Some structures hover in mid air suspended from the roof. Architecture is fanciful and creative, liberated from earthly constraints of weather, geological instability and high gravity. Flying cars, safe because they're autonomous, are much more efficient than on earth. In the distance at night is a panorama of lights embedded in the ice face as an art project, seeming like an arc of starry night sky.

Unlike an O'Neill space colony, it grows organically in place, inhabited the entire time. It didn't have to be planned in every detail and completed before it was habitable. It's a more ordinary city in that respect.
The problem is that it has the same problems as cities on earth. Why go this far to the same mistakes. It has too have greater design for it to change.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:13 PM

You can reduce hab-pressure slightly, but not by much. Or you will have to go up with the oxygen ratio, which comes with its own problems. There are good reasons for staying at Earth-like atmospheric pressure (like on the ISS).

I am a great fan of 50% pressure. It is low enough that you can get into a spacesuit or low pressure habitat without waiting. It is low enough to make some building problems less severe. It is high enough that normal cooking is possible as the temperature of boiling water is ~80C.

You may have to go slightly above 20% O2 but not too much.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 04:18 PM
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:18 PM
If you are trying to melt ice for its water, (and to make a habitat bigger) one advantage of an ice habitat is that any waste heat can be used for that very thing, melting ice in new areas. You just have to find a very efficient way of moving the heat to where you need it.

I'm not sold on this idea but I did want to point that out.

I am not sold on it too. It is not "the" solution for habitats. But it is one solution with the advantage to have large caverns. Something people will like. I do wonder how good ice will retain the air. But bubbles inside ice cores are used to determine the air components of long gone eras so it should be pretty impermeable.

One thing that is important IMO is the rule that habitats need to be stable both pressurized and unpressurized. Difficult but an important safety feature. Ice caves would have that feature.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:21 PM
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)

If I got my info from diving right it would be slightly too high for getting into spacesuits without pressure adaption. Otherwise right, really no need to have full sea level pressure, every reduction helps. On the ISS full pressure has advantages in transfer from and to earth. Not an issue for Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/14/2016 04:51 PM
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)

If I got my info from diving right it would be slightly too high for getting into spacesuits without pressure adaption. Otherwise right, really no need to have full sea level pressure, every reduction helps. On the ISS full pressure has advantages in transfer from and to earth. Not an issue for Mars.

Keeping O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 09:31 PM

Keeping O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.

Sounds good to me, if 40% partial pressure is really to high because of fire hazard. Some quarters like hospitals for some diseases may want to have higher oxygen partial pressure than 75% of sea level but for such areas special precautions against fire would be possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: drzerg on 10/14/2016 09:44 PM
with pressure you should consider long time health implications and pregnancy. people can live safe at 4000m on earth. so this pressure is not harmful regardless of O2 value.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/14/2016 10:07 PM
Some people can live at 4000m but it can cause severe problems for pregnancy. Basically unless the population is already genetically adapted to altitude there aren't going to be any babies.

Hypoxia, fetal growth and early origins of disease: the Andean curse on the Conquistadors (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2075320/)

Best keep pressure at sea level. There are enough unknowns with the low gravity and high radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 10:09 PM
I agree 4000m is a little extreme.
OTOH 3000m is much more doable. 10000 feet.
The grand canyon rim is about 9000 feet. Probably a little less.

EDIT:
I was way off 6800 feet for grand canyon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: obsever on 10/14/2016 10:49 PM
Best keep pressure at sea level. There are enough unknowns with the low gravity and high radiation.

The radiation problem can be hopefully solved with enough shielding. I'm afraid that the low gravity could turn out to be a show-stopper for pregnancy and child's growth. Perhaps a section of the habitat will be needed to rotate to provide artificial 1 g and children and pregnant women should spend most of their time there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2016 11:10 PM
I agree 4000m is a little extreme.
OTOH 3000m is much more doable. 10000 feet.
The grand canyon rim is about 9000 feet. Probably a little less.

EDIT:
I was way off 6800 feet for grand canyon.

Here is a 2 km diameter dome, just off the vistor center of the grand canyon.
Are there similar steep hills in Vale Marineris or elsewhere?  Perhaps not the most practical solution  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2016 11:26 PM
Not spectacular enough?

Bigdome2 with ITS!!

A pure tension structure, buildings inside are also seal-able in case the main dome fails; redundant protection.  Vegetation grows in the dome, but outside the buildings.
The overall structure is protected by a mini magnetosphere, similar, but more powerful, than those existing on the moon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/15/2016 12:21 AM
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.

I think you're confusing pressure vessels with making things gas-tight. "Arches, vaults, columns and other compression load bearing structures" won't help at all because your building will not be under compression at all. It will be under tension. The atmospheric pressure inside will try to push things apart form the inside.

Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

Cracks in rock in a cave or tunnel aren't a problem, a thin membrane to prevent gas from escaping is easy, but there is no such thing like a "thin membrane pressure vessel". In a cave the pressure would be countered by the weight of the rock above and around it. If you don't have that weight you have to counter the pressure by tension in your pressure vessel and this not going to be a thin membrane then or bricks, or anything short of steel or aluminum, or massive reinforced concrete.

And yes, you need more than just pressure vessels to live in, but they're the biggest things you need and if they fail you won't have any time to fix things, because you will be dead immediately. They are the first and most crucial thing you need. And if you want to live and grow food in them, they need to be big and you need many of them and they need to be safe.

I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:08 AM
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/15/2016 01:32 AM
A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material ...

As your average party balloon, which can sustain a pressure differential of >1 atm, demonstrates. (Of course, you'll want to use a material that doesn't 'pop' when punctured!)

Quote
In my scenario the arcade structure provides all [the abrasion resistance and ballistic protection] allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

You could just inflate it inside a cave, or lava tube or even a constructed tunnel. This helps provide radiation protection, as well. On the surface, you could just shovel regolith over it (possibly in sandbags, to prevent abrasion), but a 1 atm differential would easily sustain the weight of the few meters required.

Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/15/2016 01:38 AM
Regarding "flat plains" and building regolith-covered habitats.
Last time I checked, even Mars plains are not that flat. They have these nifty depressions called "craters", of all sizes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:43 AM
Let's design my 2 km dome:

For a thin walled sphere, s=P*r/2t
s= strain
P= Pressure
r= radius
t= thickness

Supposing we use high strength steel, and a thickness of 0,5m I find that the dome needs to be made from 20% steel; the rest can be plexiglass panes set in the structure.  Safety factor of 3.
The mass is 10 million tonnes, plus the plastic and the ground anchors. If we stuff 1million persons in there, it's 10 tonnes of steel per person.
Seems heavy.

Interestingly, if we design smaller domes, let's say 200m in diameter, the mass ratio goes down linearly with the floor area. So instead of 10 tonnes per person, it's 2 tonnes per person.
So 100 x 200m domes have the same floor area as a single 2000m dome, but 10% of the mass.

So the people saying bigger is better may be wrong, in this case.  We should plan for 100 small domes not for a single large one.

Seems a lot safer, as well.

Spreadsheet is joined.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:55 AM
A bit closer. :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/15/2016 02:36 AM
A few related ideas:
I think mars colonies are likely to grow in a fashion resembling plants.

The "Leaves" are the solar panels and perhaps low pressure greenhouses or pipes carrying algae to exploit photosynthesis. In any case it will gather solar energy and like leaves I expect this portion to be somewhat fragile and not too hard to replace/repair.

Below ground you have "roots" being mining tunnels that are later buttressed to become living areas and storage areas.. which are a bit like a plant's tubers if you like. These roots would also form new shoots to the surface like some plant types.

One of the main forms of ISRU will be organic chemistry, combining CO2 and N from the air and ice from the soil along with some other elements. There are so many useful materials you can make from this small easily accessible group of CHON elements that are also the key elements that plants (and all life) exploits. I think there will be constant economic pressure to do as much as we can with these ingredients and, as much as practical, minimise requirements on things like rare earth metals that might have to rely on distant mines.

Im sure this plant analogy would have heaps of exceptions but it is easy to see why a mars city has reasons to move somewhat further in this direction than an earth city.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 02:52 AM
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 03:08 AM
O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.

I've seen 1/2 atmosphere before, e.g. here:

(http://settlement.arc.nasa.gov/75SummerStudy/table4.3.gif)

http://settlement.arc.nasa.gov/75SummerStudy/Chapt4.html#Life
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/15/2016 03:21 AM
Im also fairly enthusiastic about some general ideas mentioned here:
Containing water under an oil layer on Mars (http://forum.nasaspaceflight.com/index.php?topic=40628.msg1555177#msg1555177)

The key points I think are important:
*There are apparently vast bodies of ice on mars, even near the equator, under say ten meters of regolith.
*It is possible to liquify large amounts of this water "for free" using waste heat. This might even happen inadvertently.
*Large bodies of water for free are potentially very useful, but you would also be making your previously solid ground very unstable. The regolith would want to collapse and fall through the lighter water.
*The solution could be to let the regolith cover fall through and replace it with a layer that is lighter than water.

 This does not need to be an "oil". It could be anything from plastic bubbles to rafts to traditional engineering. The point is just that your roof material is less dense than your water and you can extend your roof incrementally, unlike some sort of loadbearing arch you have to keep redesigning as the ground softens more and more beneath it.

In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/15/2016 03:40 AM
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.

So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 03:55 AM
So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?

You won't have to organize a burial for the suffocated colonists.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/15/2016 03:58 AM
 I suppose there's a silver lining of some sort to be found in nearly everything.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/15/2016 07:40 AM
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.

Regolith in direct contact with a membrane type pressure vessel would be abrasive to it for one, necessitating more layers for protection.  The regolith would also be extremely cold which would cool both the membrane material and the interior habitat, the cooled membrane could lose strength and the cooling of the interior is undesirable for condensation reasons.  It's preferable to have maximum insulation around the habitat and to expel heat only via a radiator so you can have full control over the temperature inside.  Having a small ambient air, aka near vacuum, gap between the membrane and any solid object is virtually the best insulation you can have.  This applies to the ground too so I would put foam on the ground and then place the inflatable habitat onto that.

The direct regolith covering of an inflatable habitat is a good strategy for very early habitats, using essentially full Bigelow type habitats with their extensive layers and insulation would allow direct burial.  The construction I was describing was intended for mid to late phase settlement in which more local materials are used.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:45 AM

So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?

That's why I keep arguing that any structure designed needs to be stable both on ambient pressure and pressurized. It does not make construction easier but it is doable. Neglect that requirement on peril of your life.

Edit: Impalers suggestion to build domes for radiation protection and inflate structures inside is one of the possible solutions. Not necessarily the best but one feasible solution
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:50 AM
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/15/2016 09:02 AM
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 11:07 AM
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:43 PM
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Some disasters are relative.  When, not if, a mini magnetosphere generator fails, if it can be repaired in such a time that inhabitants do not get too much radiation dosage ( a few months imho) then it's just an event.
It will be possible to have two mini magnetosphere generators, then the issue is only can you switch from one to the other without problems. 
So yes, it would be interesting to see if these can function on Mars, or if the atmosphere, thin as it is, makes the idea fail in some way.
There are papers on the lunar mini magnetospheres, they pop out on google easily.  There is a british group investigating them for space vehicle protection.  I believe the american version of the idea failed, somehow.

The solution that will win out is the one that requires less energy overall.  Domes inside a lava tube seems  interesting, as you separate the pressure requirement from the radiation protection requirement, and you don't have the abrasion problems.  Lava tubes are obviously stable, over millions of years, structurally. The chemical environment inside lava tubes is unknown though, so exploration is a basic requirement.  And lighting the lava tube in non trivial, compared to using natural light. Basically requires 1m2 of solar panel for each m2 of lit area, more or less?
As are experiments in reduced gravity at 1/3 and 1/6th.  It's a crying shame NASA or some other group hasn't been doing this for decades, but let's hope that will be changing in the next few years.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/15/2016 02:05 PM
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Some disasters are relative.  When, not if, a mini magnetosphere generator fails, if it can be repaired in such a time that inhabitants do not get too much radiation dosage ( a few months imho) then it's just an event.
(...)

I agree that disasters are relative and that one would have time to fix the machines that create the magnetosphere. A magnetosphere won't increase disaster risk if the labor/capital/energy resources devoted to the maintenance and repairs of the magnetosphere don't compete with opportunities to increase the safety margins for other critical systems (air, water, greenhouses etc.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 02:28 PM
One fundamental problem with domes on Mars is anchoring it them the ground. It might be best to simply continue the membrane construction all around the habitat, i.e, build floors as well for every habitat, rather than try to anchor the dome to the ground.  With a floor, all forces are kept in the tension structure.

If you do use anchors, a quick calculation suggest that the bottom of the dome should be dug-in for quite a few meters and then some kind of massive footing used.  This could be covered with regolith to create sufficient inertial mass to keep the dome down.  150 times the mass of the dome for a 200m dome, 13 x the mass of the dome for a large 2000m dome.

Updated spreadsheet.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 02:37 PM

The solution that will win out is the one that requires less energy overall.  Domes inside a lava tube seems  interesting, as you separate the pressure requirement from the radiation protection requirement, and you don't have the abrasion problems.  Lava tubes are obviously stable, over millions of years, structurally. The chemical environment inside lava tubes is unknown though, so exploration is a basic requirement. 

Exploration is a basic requirement. Yes, even if they are supposed to be long time stable, the holes seen and even have been seen appearing suggest they are not infinitely stable and I would want a very thorough geological survey before I feel safe in them. Also living in a black hole is not an attractive proposition. As you mentioned maybe a lot of lighting even of unused areas may be needed for humans to feel comfortable.

And lighting the lava tube in non trivial, compared to using natural light. Basically requires 1m2 of solar panel for each m2 of lit area, more or less?
As are experiments in reduced gravity at 1/3 and 1/6th.  It's a crying shame NASA or some other group hasn't been doing this for decades, but let's hope that will be changing in the next few years.

Depends on what the lighting is for. Enough for the huaman eye to see needs very little light. 1/1000 of full light will serve quite well. If you want to grow plants, even shadow suited plants like ferns and philodendron you may need 10% of full sunlight on earth.

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 03:40 PM

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.

My current favorite is surface habs made from tensile domes, 90% transparency, with a minimagnetosphere radiation protection system.  That sentence contains a fair amount of science fiction at this time, unfortunately  ;-).

Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/15/2016 04:20 PM
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.

O2 partial pressure can be set at 2400 meters instead of sea level. That's about 75% of sea level. It is also just below the altitude where healthy unacclimated individuals suffer from altitude sickness. That level of O2 partial pressure works well on aircraft. It should reduce the fire risk in the proposed 1/2 atmosphere.

While it's well know that a high O2 level increases fire risks, I haven't be able to find actual numbers to determine an acceptable O2 level.

In relation to Mars habitats, just in case the original point has been lost, 1/2 sea level atmospheric pressure means pressurized structures don't have to as strong. Less material needed, cheaper, and more options for architectural creativity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/15/2016 04:25 PM

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.

My current favorite is surface habs made from tensile domes, 90% transparency, with a minimagnetosphere radiation protection system.  That sentence contains a fair amount of science fiction at this time, unfortunately  ;-).

Underground vs surface is probably a combination of aesthetic preference and other assumptions. I kinda prefer large underground spaces even if there are good surface solutions to radiation, think nuclear reactors are necessary and don't expect agriculture to use natural sunlight or soil. The Martian population if it's large will probably have a variety of preferences and try different living modes.

The living in the space hollowed out of glaciers notion has the appeal of having an "amazing" long term city vision but being practical to start on even in early missions, because the ice is going to be consumed anyway and a volume created inside the glacier whether you use it or not. It only works if the settlement is in that location and surface habitats would work in many locations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:10 PM
I did a little calculation on how much volume of ice would be dug out for ITS fuel.

Initially Elon Musk said 10 cargo flights to 1 passenger flights. I am aware it was a very rough estimate, nothing calculated as it cannot be calculated yet. As the cargo capacity is so much bigger now I go with 3 cargo to 1 passenger flight.

If I did not miscalculate 1 flight needs 580t of water. Multiplied by four and calculating that ice is less dense I get ~2500m of excavated volume. Make that 3000m of volume per passenger ship, because some water per settler is also needed. Assuming that a large part of that volume would be open space it is not  enough to give a decent living space for all. But it could provide a good part of the needed living space and would give open spaces to go to and not be confined to closed habitats all the time.

I start to warm up to ice, hadn't considered it before.

The concept would avoid some of the problems of other suggestions. Digging into the ice and occupy all the volume with habitats would make them vulnerable to moving of the ice, much less critical with open spaces around the habitats. Insulation and thermal management would also be easier. Disadvantage is that the volume is not enough for all settlers. But that may not be a disadvantage really. Different types of habitats will be good to have.

It would require quite significant thickness of ice to maintain a cover above the caverns that is safe from caving in. Also thick enough to contain the pressure inside the habitats. I don't want to calculate it. Regolith cover will help in containing pressure, but the ice has to hold the regolith while not yet pressurized too. I leave that to the civil engineers and geologists.

Industrial construction and agriculture would mostly be elsewhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/15/2016 09:09 PM
I did a little calculation on how much volume of ice would be dug out for ITS fuel.

Initially Elon Musk said 10 cargo flights to 1 passenger flights. I am aware it was a very rough estimate, nothing calculated as it cannot be calculated yet. As the cargo capacity is so much bigger now I go with 3 cargo to 1 passenger flight.

If I did not miscalculate 1 flight needs 580t of water. Multiplied by four and calculating that ice is less dense I get ~2500m of excavated volume. Make that 3000m of volume per passenger ship, because some water per settler is also needed. Assuming that a large part of that volume would be open space it is not  enough to give a decent living space for all. But it could provide a good part of the needed living space and would give open spaces to go to and not be confined to closed habitats all the time.

I start to warm up to ice, hadn't considered it before.

The concept would avoid some of the problems of other suggestions. Digging into the ice and occupy all the volume with habitats would make them vulnerable to moving of the ice, much less critical with open spaces around the habitats. Insulation and thermal management would also be easier. Disadvantage is that the volume is not enough for all settlers. But that may not be a disadvantage really. Different types of habitats will be good to have.

It would require quite significant thickness of ice to maintain a cover above the caverns that is safe from caving in. Also thick enough to contain the pressure inside the habitats. I don't want to calculate it. Regolith cover will help in containing pressure, but the ice has to hold the regolith while not yet pressurized too. I leave that to the civil engineers and geologists.

Industrial construction and agriculture would mostly be elsewhere.

So in an era when there are 1000 ships per synod, they would consume 3 million cubic meters of ice, or about a slice of glacier 300m deep x 1000 m X 10m thick. They could do that for 100 synods or over 213 years before consuming a square km of a single 300m deep Glacier.

Rereading I forgot you were doing it with 4 shiploads total per passenger ship so it's only a quarter of that to match, either way it's the same order of magnitude.

It's a good illustration of the magnitude of the water resource there.


Of course they could also melt as much of the  glacier as they had spare heat for and keep it as lakes or reservoirs of water ready to pump too.

Even if agriculture is vertical and in underground spaces like that, it still makes some sense to do in in separate cells. One advantage ag has in completely controlled environments is no pests or diseases, no need for pesticides. Keeping units separate from each other and people helps prevent contamination and dealing with it if it happens.

About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 10:19 PM
About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.

If you have enough ice and I assume they will build the first settlement at a location that has, the easiest way to have a stable roof is going 30m deep for the roof of the caverns and make the roof  a dome. Then there would be no need for any reenforcement. It does require at least an ice sheet of 40m thickness, more is better.

As I mentioned, I have adjusted the ratio cargo to passenger for the higher payload of 300t instead of 100t. It is somewhat arbitrary but I need some estmate for calculation.

Title: Re: Envisioning Amazing Martian Habitats
Post by: UberNobody on 10/16/2016 12:19 AM
Here is what I've been thinking about ever since Elon started talking about 100t (now 300t!) to the surface of Mars along with ISRU production before the first human mission.

My big assumption is that water extraction for ISRU will be done with an automated open-pit mining operation.  Such an operation could easily be adapted to build habitats.

Because you are already running tons of material through an oven to extract water, it is relatively straightforward to add-on a sulfur extraction oven as well as a series of grates to filter out fine particles of regolith.  You can extract other materials as well, but I'll stick with sulfur and fine regolith for now.  They make a pretty good option for mars-crete: https://www.technologyreview.com/s/545216/materials-scientists-make-martian-concrete/

Now that you have the materials for mars-crete, a huge pit in the ground, and a lot of loose regolith sitting around, you can 3D print some pretty large structures in that pit.  Afterwords you would cover the whole thing with loose regolith, apply a liner to the inside (perhaps sprayed on), and pressurize it.

These structures could eventually be mall-sized.  Locally produced rebar would allow for some pretty epic domes and arches to be constructed that still hold up when not pressurized.  Simulate a sky on the ceiling and it could be quite comfortable to spend time in. 

Above-ground structures are cool, and we definitely need some, but underground/covered structures have a lot of advantages, especially if you already have mining operations going on for ISRU.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/16/2016 12:24 AM
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.

I've shown you this research before, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070005041.pdf

https://en.wikipedia.org/wiki/Limiting_oxygen_concentration#cite_note-6

Oxygen percentage is the dominant factor, not partial pressure though their are MINOR effects from pressure.  Inert gasses not only quench and slow combustion, if they are high enough they can prevent ignition in the first place.

Lungs operate on partial pressure because they are basically gas to liquid diffusion devices that seek to balance gas pressure.  Fire is an exponential chemical chain reaction which is why we can describe a fuels ideal mixture ratio with air or oxygen that becomes combustible, below critical ratios the chain reaction can not sustain itself due to the deadening effect of the inert materials, this is very much analogous to criticality in a nuclear chain reaction.

The two processes have nothing to do with each other and people who have a little bit of understanding about lungs have been trying to slap that model onto fire without understanding the difference, classic 'reasoning by analogy' and it's been repeated sooooo many times on these forums that many people believe it, partly because they want too.

On ISS the maximum oxygen concentration for normal operations is 24 percent in most of the structure and 30 percent in the airlock.  The partial pressure of oxygen is maintained between 2.8 and 3.4 psi.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/16/2016 12:42 AM
Do we know ... um ... anything at all about combustion in Mars gravity? The microgravity combustion experiments (Saffire) at least seem to indicate gravity might be a factor in what atmospheric conditions would pose a fire risk.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Optimist on 10/16/2016 01:57 AM
For those interested, the idea of tunneling into a glacier, and making chambers for a startup colony, was discussed some in this thread, about a year ago.

http://forum.nasaspaceflight.com/index.php?topic=34667.880



Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/16/2016 10:01 AM
Great picture UberNobody... is it from Italy? Have people come across vaguely similar architectures in other cultures? One is the covered bazaar in Istanbul which is several centuries old. I do believe that on Mars, it will be important to recreate and mix cultural architecture from everywhere on Earth. Not to perpetuate ethnic differences but to celebrate the diversity of our civilizations as a new civilization is born. Think of USA and other Western nations celebrating ancient Greco-Roman culture through the architecture of important buildings; I think Mars should celebrate the diversity of our architectural treasures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 02:26 PM
Maybe when we have sealed and pressurized huge lava tubes. Util then it will be form follows function. There will be strict requirements forcing the design.

Though Elon Musk seems to have a personal dispense from these rules. Look at Crew Dragon and ITS. They both look like from an italian designer for the next great space opera movie. Absolutely gorgeous.
Title: Re: Envisioning Amazing Martian Habitats
Post by: launchwatcher on 10/16/2016 04:19 PM
Great picture UberNobody... is it from Italy?
It's the Galleria Vittorio Emanuele II (https://en.wikipedia.org/wiki/Galleria_Vittorio_Emanuele_II) in Milan.   One of the world's oldest enclosed shopping malls.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/16/2016 05:09 PM
About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.

If you have enough ice and I assume they will build the first settlement at a location that has, the easiest way to have a stable roof is going 30m deep for the roof of the caverns and make the roof  a dome. Then there would be no need for any reenforcement. It does require at least an ice sheet of 40m thickness, more is better.

As I mentioned, I have adjusted the ratio cargo to passenger for the higher payload of 300t instead of 100t. It is somewhat arbitrary but I need some estmate for calculation.

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 10/16/2016 05:32 PM
I would think something like the LowLine in New York City would be more functional and practical in the long run.
http://thelowline.org/about/project/
good rendering http://thelowline.org/wp-content/uploads/2016/06/park-plans-lowline-lab-web.jpg
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 05:58 PM

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.

Loose regolith would be my strong expectation. Yes, it would not contribute to bearing the load. That's why I said a sufficiently large ice cover is necessary.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 07:52 PM
A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material ...

As your average party balloon, which can sustain a pressure differential of >1 atm, demonstrates. (Of course, you'll want to use a material that doesn't 'pop' when punctured!)

Quote
In my scenario the arcade structure provides all [the abrasion resistance and ballistic protection] allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

You could just inflate it inside a cave, or lava tube or even a constructed tunnel. This helps provide radiation protection, as well. On the surface, you could just shovel regolith over it (possibly in sandbags, to prevent abrasion), but a 1 atm differential would easily sustain the weight of the few meters required.

A party balloon can sustain only a very small pressure differential, maybe 0.01 to 0.05 atmospheres. Also keep in mind that the strain on the skin and with it the needed tensile strength of the used material rises with the radius of the pressure vessel, even if the pressure stays the same. Pressure vessels scale very badly. Increase the size of your vessel tenfold and the walls have to be ten times as thick. It's unfortunate, but that's how it is. That's the reason that the typical SF trope of cities under big transparent domes is more fiction than science.

But yes, of course you can use a thin membrane for your building-sized pressure vessel as long as it is made from very high tensile strength material. This is as true as saying that you can travel to Mars in a few days if you have engines with a very high ISP. Hey, why not make it radiation-tight and transparent at the same time? Unobtainium can do everything, right?


One of the big advantages of Mars over open space or asteroids is that it has not only lots of inert mass laying around but also gravity. Because mass and gravity gives weight and weight gives pressure basically for free. It's an in situ resource just as water in the ground and CO2 in the atmosphere is an in situ resource.

So I think the first engineering crews on Mars will live in their ships and in pressurized rovers, maybe they will have a small pressurized hab delivered in one piece from Earth. But the first long-term crews will already live underground either in caves down in the ice or later in tunnels and caves drilled in rock.

Food will be grown either in many small pressure vessels (small because small is much easier and needs much less mass for the same sum of volume) or in artificially lighted caves. Because even at the low efficiency of solar panels and LED lights solar panels can be made very light (much lighter than pressure vessels) and 10 square meters of solar panels are lighter and easier to transport than one square meter of pressure vessel. Or use a nuclear reactor. It also means you can have large open spaces with plants underground and this is much better for colonists than living in cramped vessels while growing food in small containers with glass roofs they can't enter. This would be an expensive prison, not a colony.

Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

This gives lots of room with radiation shielding and most of it could be done automatically by machines since drilling down is as straight-forward as can be. Once pressurized you can expand them with horizontal parts even while already living there. And when deep enough you get a nice pressure gradient which makes sealing the roof easier, since the pressure at the top is less than on the bottom ;-)

Huge open spaces also give much more buffer room for controlling your atmosphere (oxygen, CO2, trace gases) and fixing leaks, while in small pressure vessels you have to tightly control everything and a leak is an immediate emergency (if your pressure vessel doesn't fail catastrophically by bursting anyway, pressure vessels that are not perfectly build are prone to do that). In a vertical space you can also exploit the fact that warm air rises and cold air falls to get some mixing instead of having to duct the air around with lots of fans. Which would be noisy (the ISS it notoriously noisy). If you have ever been in a cave or a mine you'll also know that these are much quieter than metal vessels. Living in a machine-filled pressure vessel is a lot like living in a server room.

And again: This planet has lots and lots of rock. It's free and already pressurized by the weight above it. Use it. You just have to dig some out to make room. OK, it won't be really easy, but for a million people it should scale much better than any kind of pressure vessels you have to build.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/16/2016 07:54 PM
One detail to the use of an ice cavern is that it will need to be pressurised, otherwise the ice will sublimate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 08:12 PM

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.

Loose regolith would be my strong expectation. Yes, it would not contribute to bearing the load. That's why I said a sufficiently large ice cover is necessary.


NASA has found several cases of small fresh impact craters that exposed ice under a shallow cover and the Phoenix lander seems to have exposed ice by the thrust of its landing engines under a very shallow cover:

http://www.space.com/5435-images-phoenix-lander-show-martian-ice.html

I think it may be that the regolith on top is just thick enough to protect the ice from sublimating. We don't really know how all this ice came to be where it is, but there seems to be a lot of it. Maybe the ice is mixed with a certain amount of dust and the sublimating ice then left the dust behind until the dust layer was thick enough to prevent further sublimation.

The dust/regolith won't serve any purpose for us here. If you have deep ice just drilling down 30 meters or more and then melting out caves there and pump up the water would be the easiest way to handle it. Open pit mining would be idiotic because you expose the ice for sublimation then. Even if there is quite a lot of dust mixed in with the ice melting the ice would just leave a layer of stuff on the bottom of your cave.

MRO seems to have found very thick (up to half a mile) quite pure water ice though with its radar in a few places.

We need to research this better though. And go for some ground truth. A precision landed Red Dragon with a drill would be very useful... And a Martian GPS of course. We need to plot all of this very precisely.

Lots of work ahead!
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 09:20 PM
Let's design my 2 km dome:

For a thin walled sphere, s=P*r/2t
s= strain
P= Pressure
r= radius
t= thickness

Supposing we use high strength steel, and a thickness of 0,5m I find that the dome needs to be made from 20% steel; the rest can be plexiglass panes set in the structure.  Safety factor of 3.
The mass is 10 million tonnes, plus the plastic and the ground anchors. If we stuff 1million persons in there, it's 10 tonnes of steel per person.
Seems heavy.

Interestingly, if we design smaller domes, let's say 200m in diameter, the mass ratio goes down linearly with the floor area. So instead of 10 tonnes per person, it's 2 tonnes per person.
So 100 x 200m domes have the same floor area as a single 2000m dome, but 10% of the mass.

So the people saying bigger is better may be wrong, in this case.  We should plan for 100 small domes not for a single large one.

Seems a lot safer, as well.

Spreadsheet is joined.

Thanks for putting some numbers to what is a lot of handwaving otherwise.

Hmm. 1km radius makes 3.14km^2 ground. With 1 million people this gives a population density of 318000 people per square km. This is about the density of the most densely populated urban areas in Hong Kong (which is quite the record on Earth). You'd have to fill the thing with skyscrapers.

And then you need all the machinery and of course you need to grow food. Actually you'd need to have a much smaller population density, so build more domes. And rebuild them regularly, since these things will not be long-term stable (the steel will rust, the plexiglas windows will get brittle and one day it will fail and all will die. They will die early anyway with all the unshielded radiation). Ten million tons of steel is too valuable for just a few decades.

I think getting your habitats stable for a long time is important, you'll have more than enough work even without rebuilding your habitats every few decades. I would trust a few hundred meters of rock over my head better than that and replacing/improving/expanding other things can be done incrementally then. On a geologically dead planet as Mars is the crust should be stable over a really long time (millions of years at least). Domes certainly aren't.





Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 11:20 PM
One detail to the use of an ice cavern is that it will need to be pressurised, otherwise the ice will sublimate.

Not really a point of much concern. Ice can only sublimate when enough energy is added. With no sun the atmosphere would not provide much energy for sublimation. Even on the surface providing shade would greatly reduce the rate of sublimation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 11:29 PM


NASA has found several cases of small fresh impact craters that exposed ice under a shallow cover and the Phoenix lander seems to have exposed ice by the thrust of its landing engines under a very shallow cover:

http://www.space.com/5435-images-phoenix-lander-show-martian-ice.html

I think it may be that the regolith on top is just thick enough to protect the ice from sublimating. We don't really know how all this ice came to be where it is, but there seems to be a lot of it. Maybe the ice is mixed with a certain amount of dust and the sublimating ice then left the dust behind until the dust layer was thick enough to prevent further sublimation.

Quite possible. What was said by NASA specialists during the landing site selection workshop is a minimum of 1m regolith cover is necessary to suppress sublimation in near equator locations where large bodies of water were found. Near the poles it is much less. The Phoenix lander was a polar lander so it is plausible that it found ice under a thin cover.

The dust/regolith won't serve any purpose for us here. If you have deep ice just drilling down 30 meters or more and then melting out caves there and pump up the water would be the easiest way to handle it. Open pit mining would be idiotic because you expose the ice for sublimation then. Even if there is quite a lot of dust mixed in with the ice melting the ice would just leave a layer of stuff on the bottom of your cave.

MRO seems to have found very thick (up to half a mile) quite pure water ice though with its radar in a few places.

We need to research this better though. And go for some ground truth. A precision landed Red Dragon with a drill would be very useful... And a Martian GPS of course. We need to plot all of this very precisely.

Lots of work ahead!

For early ice mining they may well use open pit mining. It is much easier to do and if they keep it shaded loss to sublimation would be minimal. Dig your trenches in south/ north orientation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/17/2016 01:56 AM
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/17/2016 05:29 AM
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.

It might turn out to be one of those "all of the above" outcomes. If drilling, digging and excavating turns out to be a highly efficient basic form of Martian habitat architecture, then we can expect all kinds of these forms to be tried and also we can expect them to be combined with all sorts of windows, domes and mirror solutions for letting in sunlight, vistas and views.

Bottom line, if we are right that excavating rock is the way to go for large, amazing habitats then expect drilling both vertically and horizontally.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/17/2016 07:14 AM
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/17/2016 12:29 PM
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

Here's a calculator: http://www.mide.com/pages/interplanetary-air-pressure-at-altitude-calculator

Depending on air temperature you'd need to drill down to about 150km. You would be way past the crust there and in the mantle. I have no idea what this means in practical terms, but nothing good I guess.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/17/2016 04:22 PM
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.

Magnetic shielding saves mass, but Martian regolith is a lot easier to come by than superconducting coils.

For example here:

http://www.orionsarm.com/fm_store/RadiationShields.pdf

To reach 0.5 rem/year in a toroidal habitat with 900m diameter and 60m thickness the mass of a magnetic shield is 12x10^6kg while the mass of a passive shield is 12x10^9kg.

So we're talking thousands of tons of superconducting coil vs. millions of tons of readily available regolith.

I don't see how putting a few meters of regolith on top of a habitat is that much of a problem. If the hab itself can withstand the internal pressure you won't actually need much on top, only for shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/17/2016 05:55 PM
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.

Drilling down gives you a hub to expand from instead of building a rabbit burrow, it can give you a lot of open space with natural light with long lines of sight and some plants all around, it makes mixing of atmosphere easier and it makes drilling down robotically easier, since going down is easier than to drill tunnels. It's all linear, set up a machine and it will go down until you stop it.

Also walking in 0.38g will be awkward, you'll be more jumping than walking anyway so you'll need high ceilings. Having spiral stairs will mean getting around will be great exercise while the workshops and living quarters can be more tight. I know it sounds silly, but at Mars gravity you will need to put load on your muscles and bones to stay healthy and doing this while sweating on machines two hours a day will just not fly in the long run. Better make people run up and down 500m between meals and work (and I guess climbing along nets will make good fun in 0.38g too), they will just do that without heaps of discipline and have fun instead while doing it. Of course you'd need elevators too. People will pass every part of the hab when getting around while seeing most of it all the time. People aren't moles.

But yes, you will also have to go horizontally from that shaft, but as a kind of hub or plaza a naturally lighted shaft with stairs and terraces and plants covering the walls would be better than a network of tunnels. I think.

I'm too lazy to try and do a render, but I think a shaft with 50m diameter and 500m deep with a gathering place with a canteen and plaza on the bottom, spiral stairs and terraces, plants on the walls with workshops, greenhouses and living spaces dug horizontally from the sides could make a place to live. A home to live in, not just a base to survive in. You'd get dawn and sunset, day and night (even weather maybe, you'll be able to see clouds through the roof and you may even get some rain if water from the air condenses on the roof  at night when it cools down), you'd be able to see what people are doing, you'd have space and still never be far from the others, you'd have most the exercise you need just by going through your day. At fridays you can have running and climbing races from the bottom up to the roof (opposite direction for the elders ;-)

But of course if we will find a nice, fat, stable lava tube with a glacier around the corner we would be silly not to take it. There's room for more than one type of hab on Mars.

(Full disclosure: I worked in a deep coal mine for a few years when I was younger. I liked it down there, it was more like a dark forest than like the countryside, but it wasn't bad at all. It was often very quiet and fascinating and no place looked like the other. I hate server rooms much more and I now work as a sysadmin and know what I'm talking about. Living in tin cans with machinery humming all around you all the time doesn't make a home.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Owlon on 10/17/2016 06:47 PM
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

I've had this thought before. It turns out, due to the thermal gradient, the temperature becomes unmanageably high before you get any useful amount of pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/17/2016 09:05 PM
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

I've had this thought before. It turns out, due to the thermal gradient, the temperature becomes unmanageably high before you get any useful amount of pressure.

I don't want to doubt your statement, you are likely right. But do we have solid knowledge about the temperature gradient on Mars? We have not done any deep drilling. There may well be other methods than drilling to determin the thermal gradient.
Title: Re: Envisioning Amazing Martian Habitats
Post by: matthewkantar on 10/18/2016 11:04 PM
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/19/2016 08:08 AM
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew

I think it's a stretch even for full earth strength people. But a rope with knots for up and a fire brigade pole for down could do the trick. Or a revolving rope for up and down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/19/2016 11:30 AM
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html


Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/19/2016 01:46 PM
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

All of the MIT buildings in cambridge ma are built on fill. They are 4 to 6 story buildings with 2 basements. They are designed to float on the fill. This was common knowledge at MIT 40 years ago.

Also of note.
One of the skyscrapers of boston has 3 piers on bedrock but the fourth is in fill and they freeze the soil around it to keep it stable. I thought it was the pru of the hancock but haven't found any references yet.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 12:59 AM
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.

Magnetic shielding saves mass, but Martian regolith is a lot easier to come by than superconducting coils.

For example here:

http://www.orionsarm.com/fm_store/RadiationShields.pdf

To reach 0.5 rem/year in a toroidal habitat with 900m diameter and 60m thickness the mass of a magnetic shield is 12x10^6kg while the mass of a passive shield is 12x10^9kg.

So we're talking thousands of tons of superconducting coil vs. millions of tons of readily available regolith.

I don't see how putting a few meters of regolith on top of a habitat is that much of a problem. If the hab itself can withstand the internal pressure you won't actually need much on top, only for shielding.

You need to look up minimagnetosphere.  It's a different concept than the close by superconducting coils.  The power requirements are in the KW range.  There are existing, natural  surface level ones on the Moon.  My worry is that the Martian atmosphere would short the plasma shell and destroy it.  But perhaps not.  If this works, its no regolith and not superconducting coils.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:02 AM
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Don't forget inertia. You can jump, but it's also harder to stop once you get going...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:06 AM
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

The most common method is to drive piles down to the bedrock.  If the bedrock is too far, you can invest in wide footings, that eventually end up to be full size, i.e. a raft.  But not much good for tall buildings, because of moment from wind and earthquakes.  That would not be a worry on Mars though.

Melting permafrost is a pain.  Again seems unlikely to happen on Mars in the first few centuries.  But the food production might run fairly hot, and nuclear reactors as well.  Wouldn't want them to sink...

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:09 AM
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

All of the MIT buildings in cambridge ma are built on fill. They are 4 to 6 story buildings with 2 basements. They are designed to float on the fill. This was common knowledge at MIT 40 years ago.

Also of note.
One of the skyscrapers of boston has 3 piers on bedrock but the fourth is in fill and they freeze the soil around it to keep it stable. I thought it was the pru of the hancock but haven't found any references yet.

And in Boston as well, freezing the soil was used in the Big Dig, and is sometime used in mining to create ice dams in the ground for persistent water infiltration problems.  But these are all temporary systems.  It would be  risky to depend on compressors for long term structural safety.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:24 AM
One idea I have been wondering about for a few years would be to build a tunnel boring machine on Mars, or the moon.  a 10m diameter boring machine can do more than 700m per month.  Run one of these for 10 years, and you get 84 km of tunnel, that could be arranged into about 1 000 000 m2 of floor.
Run a few for 40 years, and you end up with quite a bit of space.  Probably enough for Musk's million, if food production is in low pressure buildings on the surface.

Need a lot of blades though  ;-)

But you can dig in nice solid rock, rather than loose regolith, and probably have very little risk of leaks.  And don't need to worry about ice melting or not.




Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/20/2016 01:37 AM
Melting permafrost is a pain.  Again seems unlikely to happen on Mars in the first few centuries.  But the food production might run fairly hot, and nuclear reactors as well.  Wouldn't want them to sink...
I was referring to a few reasons it might specifically happen on mars though: boring down through say ten meters of regolith on mars to get to the relatively pure ice speculated to exist in buried glaciers near the equator, burying yourself under a thick blanket of regolith which I think would lead to heat seeping into the surrounding ground unless you have complicated cooling to prevent it.

I think you want your waste heat to be exploited melting ice. You should arrange it, not fight it. but then you have to work around this problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/20/2016 03:16 AM
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Yes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/20/2016 05:39 AM
build a tunnel boring machine on Mars

I think on Earth these are limited to fairly shallow grades; can't really dig straight down. But with Mars (or Moon) gravity? I wonder how quickly you could get well below the surface?

And how sharply can they turn?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 06:10 PM
build a tunnel boring machine on Mars

I think on Earth these are limited to fairly shallow grades; can't really dig straight down. But with Mars (or Moon) gravity? I wonder how quickly you could get well below the surface?

And how sharply can they turn?
The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

As a specialised form of crusher, it would be interesting to analyse the energy required vs crushing basalt into powder, melting it into fibers and using these fibers in a tension structure.  the actual number of fractures required in large scale boring might be not that high compared to fine crushing.  Perhaps a mining engineer might chip in on this?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 06:27 PM
I've found this interesting document on the closure rates of tunnels in ice sheets.
Closure if a function of pressure and ice creep, that seems fairly independent of temperature, but someone might want to do further research on this.  The images are for an horizontal ice sheet in Greenland, I believe, but the research covers many cases.  At first glance, deformation in Antarctica might be slower.

Anyway, these figures show heavy deformation in just a few years, so I would think twice about building in glaciers, even on Mars.  Ice is not all that stable, it would seem.

Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 10/20/2016 07:12 PM
Thanks for posting this! Looking at the lower figure, deep tunnels only show a deformation of 20 cm in 10 years on earth, that is not all that bad. And terrestrial glacier tunnels are not pressurised, while the ones on Mars would be under pressure, which gives an opposing force to the creep, especially under lower gravity.
If braced with pycrete like a mine shaft, or your normal lined tunnel, deformation should not be much of a problem.

I have been in quite a few historical mines, and unless they are braced, collapse and rockfalls are fairly common there, too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/20/2016 08:48 PM
build a tunnel boring machine on Mars

... how sharply can they turn?

The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

The art of digging a hole. (http://machinedesign.com/archive/art-digging-hole)

Quote
TBMs can make turns, but they're not exactly the hairpin variety. By carefully applying more pressure on one side of the cutting head, the machines can change course by about 0.125 in./ft. "A typical radius for a turn is between 300 and 400 ft," says Turner. "But we build special TBMs if jobs call for tighter turns. The tightest radius we ever dug was a 90 turn in 75 ft in a South African gold mine.

Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/20/2016 09:16 PM
Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.

That could be a very efficient use of a small number of boring machines - The one digging the spiral runs nonstop without needing to relocate to keep the tunnel system close together and the radial tunnels could be dug with pretty much whatever equipment is handy whenever one is needed.

A spoke-and-spiral plan allows for most of the work to be done on a very long continuous tunnel with the path(s) from one spot to another  being much shorter. Good for traffic through living/working space and the tailings conveyor for the big TBM never gets very long. If an unstable patch of rock is found just keep going and seal off that section later and abandon it.

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/20/2016 10:28 PM
A spiral would be large. Maybe a good design later. I imagine they start at a cliff and go in there horizontally. Do whatever length is convenient and drill more parallel straight tunnels starting at the cliff again. If you get deep enough into solid bedrock you can make quite large caves. Big spaces will help feel not too enclosed.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 12:04 AM
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.
Title: Re: Envisioning Amazing Martian Habitats
Post by: R7 on 10/21/2016 06:48 AM
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Sure, for anyone who can comfortably do 3' vertical jumps on Earth...which is very elite club.
Median for average Joe aged 21-30 is 22.1" and 14.1" for regular Jill.
http://jumpshigher.com/average-vertical-jump
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/21/2016 07:51 AM
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 11:58 AM
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.
I agree it is too tight.  I confused diameter and radius :-)  400m radius is the number I should have used.   The bore is probably a little large as well, at 20m.  In a text referenced in earlier posts they mention turns with a 90m radius were made, but its probably not a good idea.
Just imagine a slightly wider spiral.

One interesting characteristic of this idea is that we should be able to cost this fairly easily.  It's the cost of bringing a 400  (?)tonne machine to Mars, plus the cost for a large (2 MW?) solar array to power the tunnel boring machine and power the conditioning system.  A maintenance crew, and the value of the power used for 2 years of operation.  Could serve as a bench mark compared to other solutions

I wonder how large a bubble you can get from 400 tonnes of reinforced plastic, and what might be the mass of a regolith crusher that produced enough material to cover it, produce a stable compression structure to offset the internal pressure and what would be the energy used?

From an urban standpoint, it's a very controlled environment, somewhat akin to an utility model.  Looks like a 1950 theoretical architectural exercise.  Would they sell or rent m3 ?  From an investment standpoint, you should be able to rent out space very early in the project, by closing off completed sections.

Again, I wonder how this would compare to a more organic growth of individual domes/habitats, etc..

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 12:05 PM
The Hard Rock miner's handbook is joined.

This is really used in the industry, and contains all kinds of helpful rules of thumb and design metrics for conceptual designs such as the ones we are looking at here.

Enjoy, quantify and document  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/21/2016 03:01 PM
Well since we're talking about tunnel boring machines again, it's time to go back to my favorite topic!!! :)

https://forum.nasaspaceflight.com/index.php?topic=34667.msg1362562#msg1362562

Very nice post. The mental model is absolutely the right one, in my opinion. Transporting one large machine that will produce tens of thousands of cubic meters of long-lived, reliable, robustly pressurized, radiation-protected habitat enclosures is definitely the way to go in terms of habitat architectures. The energy cost is not a problem, because only energy-rich overall architectures can lead to expanding permanent Martian settlements (anything less would have a too-high risk of dying out). So the problem is reduced to an engineering and logistical challenge of maintaining the TBM in working order, a complex but feasible undertaking for which we already have decades of transferable experience.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 03:43 PM
Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

The illustrated tunnel is a 20m long section.
Floor area  of this arrangement is 27m/m (excluding circulation and linear park).  For a 10 km tunnel, this would mean 270 000 m2 of living area.  So 27m2 per person for 10 000 might be possible, and perhaps not too crowded.

Large public buildings such as schools, stadiums, meeting halls might need a different solution though.

Hardly claustrophobic, IMHO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 05:38 PM
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/21/2016 05:58 PM
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:04 PM
I'd have thought sealed glassified would have been rather fragile.  why not just bare rock?  Inject grouts into any cracks.
Is there such a thing as a nuclear tunnel boring machine?  All I find is area 51 conspiracy garbage on the subject.  And a weird patent.  Can't we just break the rock, please?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:07 PM
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:13 PM
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?
You need walkways because you need corridors anyway, and might as well have them out in the 'open'.  You can't move from room to room at this scale of habitat.

Think of the extra volume as buffer space.  Adds inertia to the system.   And it answers some of the worries about confinement that always get raised.  And it's cheap space, because the tunnel boring machine makes a 5m radius bore or 7.5 m radius bore at about the same rate.

You need to keep the bores at least 10m from one another on Earth, for structural reasons.  You can't bring them all to the middle, too fragile.  So yes, just a few all the way through.  The laterals are much tougher to build anyway.  I'm not certain you could actually cross tunnels as I have illustrated.  much easier in 3D space than real space ;-)



Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 07:20 PM
First post here, and would like some feedback (gently).

If you give me a heat source and some water, I'm pretty sure I can cultivate life anywhere.  It might be a Dyson sphere, but energy is our challenge on Mars, right?  Your renewable energy sources are solar and wind (especially on the poles?), so to colonize you'd seed with nuclear and develop the others. 

I'll build an ice dome first.  It would be "printed" using water ice and a radial arm, and would embed a continuous fiber with each layer of accretion.  If you pressurize the inside, the tendency will be for the ice to "creep" past the fiber thread that surrounds the perimeter of the dome, but that's okay.  I might not need the fiber at all, since it only has to last a few months.

Why?  That's my growing season.  I make the walls (3D printed, remember) to be like Fresnel lenses, focusing the sunlight toward the center of the dome.  At the poles, I have a relatively CONSTANT rate of radiation for some time.  You need X amount of watts per square meter?  I make a dome X size (60m?), focus the light toward the center, and have a tiny (10m?), thin bubble of plastic to diffuse it, retain some heat (internal greenhouse, within my dome.  No wind in there), and enjoy 24/7 sunlight while my crops grow.  Need less light?  Then add pigment (like red dirt??) to your water as your dome is being formed.

I'd colonize the poles first.  And if someone would spot me about $40mil, I'd build what I'm discussing in Antarctica.  Six months on, six months off. 

Okay, fire away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 07:24 PM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 08:07 PM
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)

I'm sure a lot of tunneling will be done but at first it will be much easier to build pressure vessels on the surface. That thermal tunneling machine hasn't even been demonstrated on Earth. Too many unknowns to remotely evaluate the feasibility. Welding steel panels together is simple.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 08:15 PM
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)

I'm sure a lot of tunneling will be done but at first it will be much easier to build pressure vessels on the surface. That thermal tunneling machine hasn't even been demonstrated on Earth. Too many unknowns to remotely evaluate the feasibility. Welding steel panels together is simple.
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 08:27 PM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 08:44 PM
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.

ITS will be a mass-rich but volume-limited architecture... I say use the mass. Steel sheets should be a easily manufactured and recycled commodity on Mars, so once there are maybe 3 or 4 habs that size which would have room for ~1000 people) should not be necessary to send any more.

AFAIK there's no way to join pre-fabbed carbon composite panels together with near-parent material strength on site in extreme cold & near vacuum - welding in those conditions is a lot more straightforward. Nor is there a simple way attach interior and exterior structures, or to recycle them at end of life. Plus, carbon fiber is much worse in compression/shear/puncture loads, so piling regolith on top is sketchy.

If you want a semi-permanent large composite hab, take the engines off a ITS ship, lay it down sideways in a trench, push regolith over it, and build decks inside the pressure vessels and prop tanks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 08:47 PM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours. 

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?
Not all plants grow correctly with 24h sunlight.  I'm working currently on an ... industrial medicinal plant production facility (60 000 ft2) ... and it will be operating on 12 hour shifts, lights on/lights off, since the rest period is required for maximum plant production.  The optimum light level for the plants is 250 W/m2 using halogen lamps, and almost 50% of the energy turns into latent heat, as the plants need to evaporate for their production/growth phase. 
Plants in the wild have long rest periods, when they do not add much mass, and poor productivity compared to what can be achieved under controlled conditions with artificial lighting.
As an interesting aside, the plants also need a certain amount of wind to stir them up everyday, of their stalks do not develop properly and they eventually collapse under their own weight.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 08:52 PM
I think the fresnel lens info is buried in the external link, or maybe in my head I just assumed that the ridges in the wall doubled as lenses as well as structure for the print head to move on.

I'm really dubious of ice holding pressure. Its use as radiation protection, structural support, light gathering, and constant maintenance seem enough without relying on it for something so critical. At least to start with.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 08:57 PM
I think we may need to look into dividing the habs into different phases of exploration. I like the ice house ideas for initial deployment, dragon sized to single ITS landings per location per synod. The TBM (Tunnel Boring Machine) hab ideas seem further down the line, once there are multiple ITS landings at each location per synod.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 09:03 PM
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.

ITS will be a mass-rich but volume-limited architecture... I say use the mass. Steel sheets should be a easily manufactured and recycled commodity on Mars, so once there are maybe 3 or 4 habs that size which would have room for ~1000 people) should not be necessary to send any more.

AFAIK there's no way to join pre-fabbed carbon composite panels together with near-parent material strength on site in extreme cold & near vacuum - welding in those conditions is a lot more straightforward. Nor is there a simple way attach interior and exterior structures, or to recycle them at end of life. Plus, carbon fiber is much worse in compression/shear/puncture loads, so piling regolith on top is sketchy.

If you want a semi-permanent large composite hab, take the engines off a ITS ship, lay it down sideways in a trench, push regolith over it, and build decks inside the pressure vessels and prop tanks.
300 tonnes of steel fits into 100 m3 with space to spare.  There should be something like 1000m3 in a cargo ITS, no?  Not that limited in volume.
I agree the joints might be an unsolvable problem.  And welding on Mars should at least be free of oxydation problems  :-)  Talk about an inert atmosphere.
However, it should be possible to create tension resistant connectors for carbon fiber panels, and then seal the joints with silicone?
I believe the ITS tanks will actually be built for higher pressures than 100 kPa.  And need lots of fancy work to resist the liquid oxygen.  So something of a waste, no?

Trench and cover construction is an alternative to using tunnel boring machines, and despite its apparent simplicity, it doesn't actually always win out against TBM construction.  TBM are not much good for subway stations though, or their martian equivalent, and that is where I think trench and cover might be compatible with the tunnels, allowing for larger spaces for public needs.

Steel is wondefully ductile, but you can mitigate the risk of breaking carbon fiber structures by doing what they to on Earth for fiber glass underground fuel tanks (or should do, not all contractors are honest!) and grade material according to size, and only use very fine materials for the first layer neat the structural cylinder.

Again digging is not all that more efficient than boring.  Specially if you don't have cheap explosives handy.




Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 09:06 PM
I think we may need to look into dividing the habs into different phases of exploration. I like the ice house ideas for initial deployment, dragon sized to single ITS landings per location per synod. The TBM (Tunnel Boring Machine) hab ideas seem further down the line, once there are multiple ITS landings at each location per synod.

Absolutely, it's not one size fits all.  And location will likely play a part as to what materials are available on site.  Giving priority to volatiles, or illumination (energy) might limit what is available for buildings.

To refer to the title of this thread, Amazing Martian Habitats will probably not be what we call the first construction shacks :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 09:30 PM
I dunno, I find the idea of any hab that uses in situ resources to increase its livable space pretty amazing! The more near term and realistic the more amazing it seems.

I've read a lot of sci fi so tented over valleys, lava tubes, tunnels and domes all seem rather old hat ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/21/2016 09:39 PM
What structure doesn't require some maintenance?
I brought up one a few posts back though you might consider it academic since we are not fish. Gravity tends to order things into layers by density.
Containing water under an oil layer on Mars (http://forum.nasaspaceflight.com/index.php?topic=40628.msg1555177#msg1555177)

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/21/2016 10:08 PM
There won't be a one size fits all solution. A variety of habitat types will exist in parallel. Tunnel boring is a great way of operating but it needs solid rock to work in. People will want a view of their environment available. Even the best flatscreen would fill that psycholocial need. Will there be suitable rock at the landing site, near enough to water? Probably yes but it needs to be part of the site selection. There will be surface habitats, steel, aluminium or composite.  I also believe there will be ice cave habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 10:19 PM
I like the oil layer idea, and wondered if anything would be able to decrease sublimation without decreasing the melting point too much.

I haven't browsed all the threads, so I'm not sure if this is covered, but nature may have an answer to what a colony could look like.  Want to see a settlement with lots of domed roofs that functions as a colony?  Just look at a wasp's nest.  Scale it up by several thousand, lay it flat and build it out of ice.  The advantage is that the roof stays under compression and not tension, and tension is minimized to the perimeter of the nest.  The perimeter could be canyon or valley walls.

As a side note, using smaller hollow "spheres" of water ice to build might accomplish a lot in terms of insulation and creating a pressure gradient from the inside to the outside.  Think of it as concentric circles, with the pressure in each one holding a fraction of the psi more than the one outside of it.  No, ice may not hold a full 14.7, but if I had 30 layers of "honeycomb" made from hollow spheres of ice, and each layer had .5 psi more pressure than the one before...you get the point.  I'm just creating a laminate for my dome, really, and the gradient never exceeds the breaking pressure on any one layer. 

I'd rather not exceed the thickness where my lower wavelengths would be absorbed in the ice.  I need some infrared to make it through, but I can't hold pressure if I stay thin. 

Anyone care to spot me $40 mil so I can test this in Antarctica?  Most of that is for the nuclear reactor I'll need, of course...  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/22/2016 12:23 AM
You definitely want to use carbon fiber not steel, perhaps toughened. But it is 10 times stronger for the same weight as steel. And is good in compression, too.

Or other fibers whose properties are enhanced at lower temperatures. For instance, Dyneema (UHMWPE) has just as high strength to weight ratio but usually isn't used for aerospace since it eventually creeps under load at room temp and doesn't work well at elevated temperatures. But with Mars' cold temperatures, it's a perfect material and a stupendous radiation shield and it monomer (ethylene) is actually the easiest plastic monomer to synthesize on Mars, so can be eventually produced via ISRU. It's also translucent so lets in sunlight.

A dome is sent in panels, and can be designed for easy construction, including joining..
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/22/2016 12:40 AM
I'm opposed to sending any more construction materials than are absolutely necessary. 

Send a robotic habitat builder.  Drop it near a glacier.  Build domes of ice.  From space, it's going to look like honeycomb.  Synthesize the polymers you'll need to make the ice work as a transparent construction material.  Automate crop growth.

THEN send people.  Until we successfully grow food there using the materials present, it's just a one-way trip.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/22/2016 12:56 AM
That's not required if we have a decent spaceship, like SpaceX's ITS spaceship or NASA Langley's Hercules. It can be a two-way trip even before we're growing "crops."
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/22/2016 01:10 AM
I'm opposed to sending any more construction materials than are absolutely necessary. 

Send a robotic habitat builder.  Drop it near a glacier.  Build domes of ice.  From space, it's going to look like honeycomb.  Synthesize the polymers you'll need to make the ice work as a transparent construction material.  Automate crop growth.

THEN send people.  Until we successfully grow food there using the materials present, it's just a one-way trip.

It's not a one way trip if you can come back; at worst you fail and need to return.  But it would be a good idea to send the fuel production facility and make certain you at least have the return fuel. 
People do have a certain usefulness ;-)  but perhaps I'm biased.
Food is not all that heavy, it's really water that is the problem, usually, and Mars is stuffed with the stuff.
That's one of its good points compared to the Moon.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Aussie_Space_Nut on 10/22/2016 03:10 AM
I expect that the first habitats on Mars will be flown in aluminium cans of one form or another. Sole purpose to support the construction crew while they build the first "permanent" habitats.

I like steel as others have suggested for these first "permanent" habitats. Yes steel made on Earth and ferried to Mars. Perhaps Stainless Steel?

https://en.wikipedia.org/wiki/Nissen_hut#/media/File:Munition-store.jpg (https://en.wikipedia.org/wiki/Nissen_hut#/media/File:Munition-store.jpg)

These Nissin Huts are still "up" since WW2 even in what I imagine is a somewhat corosive setting.

I think a "Nissin Hut" designed specifically for Mars is easily doable. Covered with regolith for radiation protection. The WW2 versions had a concrete floor but perhaps for Mars a steel one would be better.

Once you have a decent sized work crew living in the Nissan Huts you can begin major works. I especially like the Tunnel Boring Machine concept.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/22/2016 05:20 AM
I think a "Nissin Hut" designed specifically for Mars is easily doable. Covered with regolith for radiation protection. The WW2 versions had a concrete floor but perhaps for Mars a steel one would be better.

I think they would have a pipe shape. Much easier IMO to make them pressure self contained than anchor them in the ground and have those anchors take all the force of atmospheric pressure.

Maybe the shape as seen in the planetary society, is easier to build large pressure vessels. Oil or gas tanks for your home may be horizontal but the large storage facilities of the oil companies have a shape that may be more suitable for a large self contained pressure vessel.

I see this long Nissen hut shape for very low pressure greenhouses that use sunlight with transparent covers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/23/2016 11:09 AM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

The temporary fiber-reinforced ice domes which focus sunlight to their center are an interesting and imaginative idea. In terms of feedback, I had two points.

The first is that another solution to the "Mars will need a lot of energy, right?" premise is to design all Martian durables, from spacesuits to habitats, to be as long lived and reliable as possible. Since every durable product has embodied energy within it, a tunnel bored into soft rock by a machine will have the energy cost of its construction amortized over its expected lifetime of hundreds of years whereas a temporary fibre-reinforced ice dome will last only months. So maybe from this perspective it is cheaper energy-wise to tunnel into rock with light and heat from nuclear, instead of building temporary ice domes for greenhouses with "free" light and heat from the sun.

The second is that if the real shortage on Mars turns out to be people. (i.e. labour hours) rather than energy, there is less value in creating temporary buildings which produce energy but require maintenance. I don't expect Mars to have shortages of energy because it is easy and essential for Mars to be an energy rich place anyway. So Mars will probably rely heavily on nuclear in its energy mix, though Musk was wise to avoid sharing that "detail" now, which come think of it might explain why he didn't talk about how people will live there at IAC.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/23/2016 11:37 PM
You guys pretty much nailed it with the tunnels and the forest of domes:

ElonMuskOfficialCEO of SpaceX 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mfck on 10/23/2016 11:49 PM


ElonMuskOfficialCEO of SpaceX 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

I fail to imagine tunneling droids powered by electrical batteries, PV or Nuclear charged. Is the power density of current SOA batteries enough for industrial scale mining ops? I assume 'droids' to mean autonomous systems, though.

Are they planning on some Methalox ICE for ground ops? How feasible one would be?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/24/2016 12:23 AM
Power density is more than enough. And the biggest mining equipment today is already directly electrically powered with cables, for instance the largest mobile machines in the world, bucket wheel excavators.

There's this false idea that electric is "ninny" while real stuff is ICE powered. That doesnt fit with reality and hasnt for a while.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/24/2016 12:32 AM


ElonMuskOfficialCEO of SpaceX 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

I fail to imagine tunneling droids powered by electrical batteries, PV or Nuclear charged. Is the power density of current SOA batteries enough for industrial scale mining ops? I assume 'droids' to mean autonomous systems, though.

Are they planning on some Methalox ICE for ground ops? How feasible one would be?
Actually, tunnel boring machines are remotely powered.  As are the big shovels on mining sites.  At 4500V or so, you can have a really long extension.  Don't need batteries.  Large PV array, step up station to 4500V (or whatever the DC or AC current will be chosen for distribution) then aluminium cables with a tough outer shell.
see the picture bellow of the power cable for a big mining shovel.

Nothing very exciting happens in tunneling, most of the time.  So remote operation should be ok.  Semi autonomous.

Methalox is not logical, since you need to produce it from the PV or nuclear reactor anyway.  Might as well use the electrical power directly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mfck on 10/24/2016 12:39 AM
Aha! Thanks for the correction, both.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/24/2016 12:45 AM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

If you build stuff on Mars, it does not mean you have to do everything in some "new" and "imaginative" ways. Quite a number of old boring methods from Earth may work just fine. After all, they are the result of thousands of years of experimentation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/24/2016 12:55 AM
I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

Largest space for minimum landed mass. Specifically geared towards initial habs.

For levels of maintenance think roomba or pool cleaning robots.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/24/2016 01:23 AM
We can ISRU all kinds of stuff. That means we don't need unstable structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/24/2016 04:17 AM
We can add transparent geodesic domes to the list of amazing habitats after the AMA on reddit.

http://imgur.com/a/NlhVD

From page one: Initially glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 10/24/2016 05:03 AM
Just a reminder; MRO and Opportunity found montmorillonite, an aluminum bearing clay, at Endeavour Crater. Aluminum ceramics make a very strong "bulletproof glass" almost as tough as sapphire. Some can stop a .50 BMG.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/24/2016 03:19 PM
About mining droids. A reddit poster

https://www.reddit.com/r/spacex/comments/591rj1/rspacex_elon_musk_ama_answers_discussion_thread/d95380m/

suggested continuous miners for mining and for habitat building. I think they may be better suited for carving out habitats than a tunnel borer. They can build any size and shape, including narrow bends.. They are smaller, though still massive. Many of them could be sent instead of one tunnel boring machine.

(http://www.coaleducation.org/technology/Underground/images/Joy_Mining/12CM27.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/24/2016 03:39 PM
I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

Largest space for minimum landed mass. Specifically geared towards initial habs.

I'm not convinced that ice habitats have minimal mass requirements for supporting tools.

Quote
For levels of maintenance think roomba or pool cleaning robots.

I'm thinking more along the lines "it fails in 3-10 years".
There were people with the same fancy ideas of living in the ice. And they had enough $$$ to actually try it:

https://www.youtube.com/watch?v=NnBG37CPDLI
https://en.wikipedia.org/wiki/Project_Iceworm

Yes, on Mars it may be more stable. The key word is "may".
As opposed to habitats built with rock/cement/basalt fiber/plastics/steel, which we *know* would not melt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/25/2016 01:22 AM
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.

It's by far the simplest means of creating both habitation spaces and sealed spaces.  Remember that the colonists don't have any industrial base up there.  You always need to think of the simplest solution requiring the fewest shipments to the surface that can last the longest and provide the most protection.  If you can combine all of these elements with one expensive piece of machinery, it becomes solely an accounting problem and not an engineering and industrial base availability problem.

We know without a doubt that they will have power.  Parts, building materials, and supplies are another matter entirely. Soil vitrification is a well understood technology- as are TBMs. As long as they have a sufficient power source, they can create pressurized habitation areas that will last for millennia without the magnitude of replacement parts of a conventional TBM, and without the need for pressure vessels shipped all the way from Earth.  Think about the difference in living space expansion if only one trip is needed instead of 10 for the same cubic pressurized space.

You guys pretty much nailed it with the tunnels and the forest of domes:

ElonMuskOfficialCEO of SpaceX 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

What, you don't think he lurks from time to time on NSF?  Silly person... ;)

It's the nuclear part that doesn't convince.  And I don't really see the point in the vitrification either.  Don't see why it will be tougher than the rock, since it is made from the same material.  Why vitrify crystallized rock?  Might well be required in regolith or in loose soil though. Since that is not structural.  But we should be able to find places with less fractured rock, basaltic areas, perhaps, or some early sedimentation, metamorphic rock that has been reheated into suitable tough, but not too tough, material.

As far as melting goes, won't melting points/elements wear out as well?  High temperature materials are notoriously fragile... Since no thermal boring machine exists, how can we know that they will last longer than the ones we do know about, that we already use and that we can plan for? 

A few tonnes of spare cutters seems a whole lot cheaper than inventing a thermal tunnel boring machine, IMHO.
Crushing is something we have down to a fine art.  Melting in the field, not so much.  Seen many rock melters on construction sites recently?

I think it's just a convergence of ideas.  The best solutions pop up here, as  they probably pop up in the brainstorming sessions at SpaceX.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/25/2016 03:10 AM
There is a general argument in favor of Martian machines which are based on simple and well understood technology: the longer you can keep that machine going with the labor and spare parts you will have available in [...Mars Base Alpha  ;D] the more the useful output you will get from that machine over its lifetime and the bigger the contribution it will make towards making Mars Base Alpha self-sustaining. From this perspective, the bar is very high for machines which are still at low TRL's.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 03:21 AM
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 04:15 AM
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 05:03 AM
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 05:44 AM
Some pictures from the CERN cavern excavation. Looks relatively "simple". You'd need a pressurized hab to cover the access shaft.

(http://d29qn7q9z0j1p6.cloudfront.net/content/roypta/370/1961/831/F11.large.jpg)

(https://www.dywidag-systems.com/uploads/pics/DSI_Switzerland_Geneva_CERN_03.jpg)

(http://hep.phys.sfu.ca/openhouse_2008/kiosk/gallery/atlas_photos/selected-photos/detector-site/underground/0002017_04-A4-at-144-dpi.jpg)

End result:

(https://mediastream.cern.ch/MediaArchive/Photo/Public/2003/0309030/0309030_02/0309030_02-A4-at-144-dpi.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/25/2016 06:20 AM
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

The temporary fiber-reinforced ice domes which focus sunlight to their center are an interesting and imaginative idea. In terms of feedback, I had two points.

The first is that another solution to the "Mars will need a lot of energy, right?" premise is to design all Martian durables, from spacesuits to habitats, to be as long lived and reliable as possible. Since every durable product has embodied energy within it, a tunnel bored into soft rock by a machine will have the energy cost of its construction amortized over its expected lifetime of hundreds of years whereas a temporary fibre-reinforced ice dome will last only months. So maybe from this perspective it is cheaper energy-wise to tunnel into rock with light and heat from nuclear, instead of building temporary ice domes for greenhouses with "free" light and heat from the sun.

The second is that if the real shortage on Mars turns out to be people. (i.e. labour hours) rather than energy, there is less value in creating temporary buildings which produce energy but require maintenance. I don't expect Mars to have shortages of energy because it is easy and essential for Mars to be an energy rich place anyway. So Mars will probably rely heavily on nuclear in its energy mix, though Musk was wise to avoid sharing that "detail" now, which come think of it might explain why he didn't talk about how people will live there at IAC.

Thank you for the feedback.  I'll agree that a rock structure will last longer, but I'm not sure that temporary (seasonal) structures will not have their place.  Going back to the "honeycomb" view from space, I'll offer another constraint: pollination.   A beehive can presently pollinate around 5 acres of land.  Sooooo....each dome would represent a fixed portion of that area.  Oddly enough, if you can build an ice dome here on earth, reduced gravity on Mars SHOULD make it easier to build a larger dome.  It might not be 1000 feet in diameter, but an array of 7 domes (center one with beehive, six surrounding it) each with a diameter of 300 might work.  Space bees, anyone?

The consequence of growing food inside of an ice dome that could fail is...frozen food?  Seriously, in a new settlement on earth your garden might be bigger than your house.  I can sleep in a lot more places than I can cultivate; growing food is going to be the challenge.  You there, Elon?  Spot me a 10MW thermal, 2MW electric SSTAR and a glacier with some rock at a latitude higher than 74 or so, and I'll build a city out of ice.  Just drop me off in the fall and give me six (cold) months.   ;-)

One of you might be the first person on Mars.  I'm going to be the first person to eat a Martian chicken sandwich.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/25/2016 12:43 PM
Tunnels are a great idea and completely obvious when you think about it, which is probably why Elon-"first-principles"-Musk says Mars Base Alpha will be made with tunnels. It should definitely be possible to make interior cladding with ISRU techniques, one way or the other (with melting, with mixing cement, even with bricks).

Another huge advantage of tunnels is that by placing your town in exactly the right place you can conceivably tunnel over to a landing pad (far away from small, fragile surface domes) and also tunnel over, and down, to water supplies.

In one fell swoop tunnelling deals with the radiation problem, the cost-per-cubic-metre problem, the resource problem and the pressurization problem. All with well-known tech.

The Graduate was told that "plastics" was the future. I think a future Mars Graduate will be told that tunnelling is!   
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/25/2016 03:31 PM
Nice National geographic poster, Mars map and an interesting view of an early colony, with a lava tube.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 09:26 PM
You can probably fit a 4m diameter tunnel boring machine on an ITS. I think that tunnel boring is a lot harder than is being presented on this thread, though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/25/2016 09:36 PM
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.

You also won't need breathable air during construction. If you find a suitable place (no cracks in the rock) you can start pretty soon to pressurize your tunnels and shafts with compressed martian atmosphere (CO2) which would make many things easier (even cooling your machinery) and the crews working with breathing masks is much more practical than in full pressure suits.

It would be a good idea though to start with prospecting for suitable spots. You need water and solid but not too hard rock. Sedimentary stone would be ideal probably, if it is cemented. Sandstone is easier to work. Landing a small fleet of Dragons with drilling equipment, ground-penetrating radar and seismic sensors would help a lot with charting what you've got there.

Or just land a small crew on a glacier to refuel their ship and have them do the prospecting. Having a clear long-term goal ("living on Mars") has a way of focussing your efforts that open-end research rarely delivers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: S.Paulissen on 10/25/2016 09:48 PM
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.

You also won't need breathable air during construction. If you find a suitable place (no cracks in the rock) you can start pretty soon to pressurize your tunnels and shafts with compressed martian atmosphere (CO2) which would make many things easier (even cooling your machinery) and the crews working with breathing masks is much more practical than in full pressure suits.

It would be a good idea though to start with prospecting for suitable spots. You need water and solid but not too hard rock. Sedimentary stone would be ideal probably, if it is cemented. Sandstone is easier to work. Landing a small fleet of Dragons with drilling equipment, ground-penetrating radar and seismic sensors would help a lot with charting what you've got there.

Or just land a small crew on a glacier to refuel their ship and have them do the prospecting. Having a clear long-term goal ("living on Mars") has a way of focussing your efforts that open-end research rarely delivers.

I invite you to open your eyes (and any exposed mucus membranes) in high concentration CO2.  You will not be a happy camper.  Even relatively low concentrations of CO2 are not very pleasant conditions to be in, mask or no.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/25/2016 09:52 PM
I was thinking the same about a CO2 atmosphere but was not sure. If a mask covers your eye and your mouth well, I thought it might be possible.

Also fuel ISRU will yield a lot of nitrogen and argon as byproduct. If you use that it would be better. But if you lose too much of it that would not be good. You need it for building atmosphere of your habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 09:54 PM
Still good enough if your eyes are covered by the mask. Or you can fill with nitrogen and Argon which are plentiful in Mars' atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/25/2016 11:43 PM
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/26/2016 12:00 AM
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.

For tunnel boring, maybe it will be teleoperation as far as possible and if people need to be physically there then they will be in these new-style pressure suits which are more comfortable to work in.

You can probably fit a 4m diameter tunnel boring machine on an ITS. I think that tunnel boring is a lot harder than is being presented on this thread, though.

I agree that tunneling will be hard, but the payoff is huge in terms of the quantity, quality, connectivity and longevity of the pressurized volume, so it seems like the kind of challenge worth rising to.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/26/2016 01:19 AM
Well, look at that! A vitrification machine.  Fascinating.
Subsurface planar vitrification?  I still don't see how that makes the caves stronger though.  Glass is a fragile material. There appear to be carbonates on Mars, this was probably also discussed no end but is Martian cement and concrete possible?

I agree we are throwing tunnel boring machines about in this discussion with wild abandon. A brave soul might perhaps do a spreadsheet of construction costs on Mars?  Distances, masses, energy?  Technological readiness?


As far as Lava tubes go, why not just grind down the living area?  That would solve the sharpness issue?  Anyway, if this has been discussed before, I won't go over it again.  It does seem a bit premature to write off an idea that has never been investigated, and Mars may have had some erosion in the past for some of the caves...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/26/2016 01:57 AM
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.
But Mars' air has even more oxygen with it. That means you could catalytically oxidize the CO to CO2 without extra energy (potentially even harvesting energy that way).
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/26/2016 08:18 PM
For a very early hab - what about something that's like a tennis bubble? It could be more easily stowed onboard inside the ITS cargo space.

(https://www.ssprd.org/portals/0/Littleton%20Golf%20and%20Tennis/LittletonTennisBubble.jpg)

(http://arizonstructures.com/wp-content/uploads/2013/02/slide03.jpg)

The entire thing could be inflatable for ease of deployment. Just stamp the ground flat first. Inflatable arches would provide initial structural support, later reinforced by cables.

Gives you a lot of floor space to work with.

You would expand by erecting more bubbles adjacently and linking them for a contiguous workspace

(http://www.thefarleygroup.com/userContent/images/Blog%20Photos/Cary%20Leeds.Exterior%20Aerial%202.jpg)

Perhaps the Bigelow/Transhab type of multi-layered composite would be adequate protection from micro-meteorite strikes - although for big ones you're SOL.

The only thing better would be a lava tube, but those would probably come later, since they'd require quite some time to prepare and convert to a larger living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/26/2016 09:05 PM
For a very early hab - what about something that's like a tennis bubble? It could be more easily stowed onboard inside the ITS cargo space.

The only thing better would be a lava tube, but those would probably come later, since they'd require quite some time to prepare and convert to a larger living space.
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.
Joined here are a few calculations for dome design.  I have added a column for flexible dome design.  It uses steel, but it should be a good analog for carbon fibre woven cloth plus insulation.  For a 100m radius dome, I'm getting about 10000 tonnes.  A 50m radius dome would be much lighter, you can test this if you want with the spreadsheet.

Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 06:57 AM
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/27/2016 07:30 AM
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

That same internal pressure he mentioned will require some serious pegs. Mars' atmospheric pressure is 0.6% of earth's. To keep a dome inflated on earth, you need the internal pressure to be slightly higher than the outside. Even if your dome isn't perfectly airtight, it's easy to compensate continuously. But even at the lowest pressure that would be somewhat comfortable for humans (the partial pressure of oxygen in earth's atmosphere), any air leak would cause explosive decompression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/27/2016 07:47 AM

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

Because of the high loads. Assume only 200m. Then it is already 2000t force to be contained by the anchors. Tent pegs won't handle it, even if you use thousands of them. You would need to make every single anchor 100% safe or better use enough that any one can fail and the neighboring ones can take the load. I think it is much safer and easier to deploy using a habitat that self contains the forces by continuing all around the internal space.

Domes would require a major construction effort for the anchors and you still need to seal them airtight at the ground level. I understand the geodesic dome mentioned by Elon Musk as not providing much radiation protection. That would be done by the building inside. Which is ok, it has much less constraints in costruction than a pressure hull which does radiation protection too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 10/27/2016 01:17 PM
Inflatable buildings need to be buried.
The weight of 3 feet of dirt ranges between 210 to 330 lbs/sq.ft.
A dome 10ft in diameter and 8ft high has a surface area of 358 sq.ft. or  load of 38 to 59 tons.
A half cylinder 10ft in diameter and 16ft long has a surface area of 660 sq.ft. or a load of 69 to 109 tons.  The internal pressure of this cylinder at 14psi is 600 tons.
So piling on about 6ft of regolith will keep wall construction reasonable. 

The alternative is building with really thick reinforced walls as in a Bigelow B330 (or XBASE) if you want to be on the surface

(edited to replace snow with dirt)
Title: Re: Envisioning Amazing Martian Habitats
Post by: AncientU on 10/27/2016 01:52 PM
Inflatable buildings need to be buried.
The weight of 3 feet of dirt ranges between 210 to 330 lbs/sq.ft.
A dome 10ft in diameter and 8ft high has a surface area of 358 sq.ft. or  load of 38 to 59 tons.
A half cylinder 10ft in diameter and 16ft long has a surface area of 660 sq.ft. or a load of 69 to 109 tons.  The internal pressure of this cylinder at 14psi is 600 tons.
So piling on about 6ft of regolith will keep wall construction reasonable. 

The alternative is building with really thick reinforced walls as in a Bigelow B330 (or XBASE) if you want to be on the surface

(edited to replace snow with dirt)

Is the goal here to reduce statistical deaths from radiation, or kill people in cave-ins so that they don't have a chance to acquire a radiation-related illness?  Tunneling is also a high risk undertaking (no pun intended)... hell, going to Mars is, too.

We are focusing too narrowly on one risk...
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 01:56 PM
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

That same internal pressure he mentioned will require some serious pegs. Mars' atmospheric pressure is 0.6% of earth's. To keep a dome inflated on earth, you need the internal pressure to be slightly higher than the outside. Even if your dome isn't perfectly airtight, it's easy to compensate continuously. But even at the lowest pressure that would be somewhat comfortable for humans (the partial pressure of oxygen in earth's atmosphere), any air leak would cause explosive decompression.

THIS is why I suggest Bigelow style materials for such a structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 02:08 PM
THIS is why I suggest Bigelow style materials for such a structure.

Yeah, that's what I suggested too - what's wrong with the Transhab multi-layered walls? If they can handle the pressure difference relative to the hard vacuum of space, then why would Mars be worse than that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: ThereIWas3 on 10/27/2016 02:14 PM
what's wrong with the Transhab multi-layered walls?

They are really bulky to ship.  The walls on a Bigelow module are about 1 foot thick, and that part is not what collapses for launch.  And they are complex to manufacture.  Using local materials is a better idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 02:39 PM
what's wrong with the Transhab multi-layered walls?

They are really bulky to ship.  The walls on a Bigelow module are about 1 foot thick, and that part is not what collapses for launch.  And they are complex to manufacture.  Using local materials is a better idea.

It would be better... Long term.

      For the initial base camp and the first colonists, who will be setting up and working with the equipment to make these sort of structures, the use of Transhab style structures, even with their thick walls, would be the most suitable and SIMPLE system to set up.

      Part of the whole issue here is simplicity.  The more complex you make the set up of the initial habitats, the longer people have to be outside, increasing the probability of accidents.  This also tends to prevent the transfer of personnel to the base camp itself, for a longer duration than needed.

      The more basic the set up and construction of the base camp / first colonial structures are, the more time available to set up other things, like in situ fuel, air and water production, the setting up and initial operation of hydro or aeroponic systems for food and additional air recycling, setting up interior habitat structures, power generation systems, and maybe even a bit of scientific exploration.

      Thin walled inflatables also will run a MUCH higher risk of structural failure and tears.  A thick walled structure would be more fault tolerant and provide a significant insulation and radiation protection factor, before being buried with regolith, as time would permit.  The thick walled structure would also allow for higher internal pressures, should it be desired, than thinner walled inflatables.

      While the Transhab type structures suffer from a somewhat higher mass and bulk penalty than thin walled inflatables, the advantages would seem to far outweigh the disadvantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 02:50 PM
Cover & Cut

Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.

True.  One reason to start with a broad pressurized dome on bedrock:  expansion can be accomplished without tunneling.  Simple interior surface excavation can do it.  That is, "cut" beneath the pre-existing "cover".   

The simplest case would be a spiral ramp excavation.  For example, ramp-cut beneath a dome's "hanging garden", to add another garden terrace level.  A 2-m cut under a notional Lake Matthew 300-m water-sealed dome expands the garden by ~13 acres.  No tunnel boring, sealant application, reinforcement or vitrification would be required.  Relatively simple.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/27/2016 05:05 PM
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.

But once you've gotten deep enough, you could dig out through the sides without adding more domes.q

However, all this tunnel-boring stuff is much, much more difficult than building pressure and radiation resistant domes and arches out of marscrete blocks and/or vitrified regolith blocks, and adding an airtight layer to the inside. Especially because nobody has mentioned the supply train that gets the heaps of waste material out of the pressurized area in a meaningful amount of time required to make working in a pressurized area advantageous.

Cranes and concrete are thousands of years old building techniques. Sure, the cranes would likely contain pressurized areas, or at least be controlled remotely from those areas. These techniques are far easier to scale up as the colony grows, and need a far smaller industrial base for maintenance and spare parts, and thus would require less support from home.

Tunneling on earth is not an easy job. When things go wrong, it takes months to solve the problem on Earth, with humanity's entire industrial base less than 24 hours away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/27/2016 05:17 PM
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 05:31 PM
Zipper Truck Tunnels

...nobody has mentioned the supply train that gets the heaps of waste material out of the pressurized area in a meaningful amount of time...

Cranes and concrete... are far easier to scale up as the colony grows...

Speaking of, how about Zipper Truck tunnels?  Could be an efficient way to build bulk airlocks, and to speed entry and exit of the presumably robotic "dump trucks" and entrained open-box beds during expansion work. 

Zipper Truck tunnels would be sealed and weighted, concrete/sinter construction.  > 100 m length, with one-way traffic.  Multiple dump trucks and entrained beds would queue in the tunnels for concurrent airlock entry/exit, minimizing airlock operation time. 

"Git 'er done."

https://www.youtube.com/watch?v=7ns5UBd0gls
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 06:53 PM
Bedrock

Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.

Basaltic bedrock is pretty tough.  You'd have to excavate a long, long way down to reach a depth that needs reinforcement.

(https://patternsofnature.files.wordpress.com/2012/05/kulnura_quarry_basalt_columns_nsw_3.jpg)

Related:  Bedrock fractures shouldn't pose a problem for pressurization if leaked gas is recaptured at the surface.  A lightweight, perimeter-sealed but unpressurized canopy, such as 25-micron ETFE, could capture the fractures' leaked gas overhead.  Pressure under the canopy would equalize with the atmosphere as a pump returns leaked gas to the dome.

Also works for outgassing water and ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 08:09 PM
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/27/2016 08:33 PM
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.

Put in very simple terms, something inflated to ~14.7psi(or any significant fraction thereof) with only ~0.087psi of atmosphere countering that force will pop like an over-inflated balloon unless the material is very strong or a large amount of weight(like regolith, bedrock or ice) is piled on top of it to simulate all of the air that is piled on top of everything here on Earth.  The problem gets worse as the volume inside the inflatable gets larger.  Using a weak material and piling stuff on top of it is perhaps not a great idea, because then it will collapse if it loses pressure.

Edit: If you think that a ~14.6psi pressure differential sounds trivial, consider what would happen to most structures here on Earth if you drew a near vacuum inside of them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 08:36 PM
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.

      Interesting idea, but what would the puncture resistance be for the final structure?  Tensile strength would also likely be an issue, even allowing for internal pressure.  Especially is you plan on burying the structure.  You also have the issue of void spaces forming during the foaming process.  Trust me, I've tried to do something similar to what you suggested in a home improvement project.  Needless to say, it didn't really go as planned.

       Mind you, I am not saying that the Transhab structures should be a permanent solution, nor should it be considered as much more than a base camp structure, but they are a workable structure that would meet most of the needs for such a base camp.

      Longer term, I've considered the mixture of some form of polymer with the local regolith, to form a sort of polycrete material.  it could be foamed as an insulation material and possibly used as a direct analogue to concrete.  I considered a plastic base, primarily, because most, if not all of the needed materials and resources, to make a wide variety of polymers is readily available in the local environment.  This, then could be used to make blocks, rafter structures and domes or spheres as needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 08:45 PM
Cover & Cut

Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.

True.  One reason to start with a broad pressurized dome on bedrock:  expansion can be accomplished without tunneling.  Simple interior surface excavation can do it.  That is, "cut" beneath the pre-existing "cover".   

The simplest case would be a spiral ramp excavation.  For example, ramp-cut beneath a dome's "hanging garden", to add another garden terrace level.  A 2-m cut under a notional Lake Matthew 300-m water-sealed dome expands the garden by ~13 acres.  No tunnel boring, sealant application, reinforcement or vitrification would be required.  Relatively simple.

Problem is, you're still going to have some out-gassing through the local soil, due to about three billion years of low surface pressure.  It may not be a lot, but it will still happen.  There's also the possibility of nasty chemical reactions with the surrounding soil.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/27/2016 09:51 PM
There's also the possibility of nasty chemical reactions with the surrounding soil.

That is one point I worry about a bit. What if a slow but steady trickle of oxygen gets into the bedrock and it contains compounds that can oxidise, change the volume and cause problems? Not that I know anything about it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/28/2016 04:45 AM
I think you would still want to use some sort of spray on sealant as a barrier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/28/2016 05:37 AM
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.

I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 10/28/2016 06:11 AM
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.

If the process of creating those triangles and supports between are straight forward enough, perhaps the dome should have a bottom half that is not made of glass.  Yes, it would involved excavating a large hole, but at least you wouldn't have the major concern of anchoring.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/28/2016 07:39 AM
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 09:23 AM
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.
I couldnt find good numbers of that. Is transparency through glass similar to though fibre optic cable? You can get values like 1dB/kilometer.
http://www.thefoa.org/tech/loss-est.htm
https://en.wikipedia.org/wiki/Decibel
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/28/2016 10:22 AM
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.

If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure. How does that justify the effort of building a giant dome? The construction equipment for the dome will have a larger mass than decoration and screens to give an 'outside' feeling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/28/2016 10:38 AM
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.

If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure. How does that justify the effort of building a giant dome? The construction equipment for the dome will have a larger mass than decoration and screens to give an 'outside' feeling.

It's very important to be able to see outside and to have access to natural sunlight. The living and working spaces can be excavated vertically and horizontally into rock for radiation protection, with geodesic glass domes creating green, naturally lit environments connected into the network of tunnels. Geodesic glass domes can also be mounted on cliffside openings to create spectacular panoramic vistas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/28/2016 11:48 AM
If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure.

An hour or two every day on average are not a problem at all. Radiation hazard is constantly overhyped. Don't go out during a solar outburst.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/28/2016 12:10 PM
Martians are going to have to get used to radiation. Think of all the time people will be outside doing construction work. They will have to sleep and play in shielded areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 03:37 PM
If you're significantly below the "datum" on Mars ( which you most likely will be as almost half the surface is and all the places where it's easy to land are), then neither micrometeorites nor solar flares are a problem because even the thin Martian atmosphere brings micrometeorites to a safe velocity and blocks almost all the solar flare.

Carry on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 06:53 PM
Flare

If you're significantly below the "datum" on Mars... then neither micrometeorites nor solar flares are a problem because even the thin Martian atmosphere brings micrometeorites to a safe velocity and blocks almost all the solar flare.

Solar flare proton energy exceeds 100 MeV. 

(http://www.projectrho.com/public_html/rocket/images/radiation/flare02.jpg)

And as previously noted (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1587381#msg1587381), at energies above ~20 MeV, the flux of cosmic ray protons is increased by interaction with the martian atmosphere.  The lower the site, the greater the high-energy flux.

It would appear to be a significant problem for surface habs. 

Protection from that high-energy flux requires meters of shielding mass, or, conceivably, an artificial magnetosphere (https://arxiv.org/pdf/1406.1159v2.pdf), generated within a bubble of ionized gas.  In-atmosphere, the ions would require confinement.  Perhaps membrane + magnetic field confinement; that is, confining fields generated inside some novel high-strength balloon fabric.  ( ? )

(https://www.researchgate.net/profile/Ruth_Bamford/publication/262920173/figure/fig6/AS:[email protected]7594998914/Figure-6-The-deflection-of-a-high-energy-ion-green-by-the-electric-field-E-r-red.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 07:27 PM
Nope. Even the worst flares are dramatically attenuated by the Martian atmosphere which averages over 40g/cm^2 (the fact that flares are still relatively anisotropic helps in this case) at typical landing locations. That's more than enough.

You can see this by looking at MSL's radiation data for transit vs surface. The flares are still detectable over ambient, but the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 07:41 PM
As you can see, 30 g/cm^2 of aluminum shielding protects against all acute effects of even the worst flares. CO2 is a much better shield than aluminum, and te average Mars atmosphere thickness over the entire Mars sky (by solid angle) is over 40g/cm^2 (and remember we can do this because flares are still fairly isotropic) at attractive landing sites, plus flares are attenuated at Mars' distance from the Sun.

Source: http://www.bioedonline.org/slides/content-slides/space-life-sciences/radiation-effects/?pageaction=displaySlideDetails&tk=56&dpg=13
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 08:36 PM
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 08:41 PM
I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/28/2016 08:50 PM
I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)

It might have to be ice so it wouldn't boil if exposed to martian atmosphere
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/28/2016 08:53 PM
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  An "excess risk of 3% for fatal cancer" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that cancer mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.

It depends on what the colonists considered an acceptable risk. A man who is a heavy smoker (two packs a day), after fifty years, has a 15% change of getting lung cancer. That doesn't stop millions of smokers.

I think the additional risk would be acceptable for establishing a base, but if Musk and his supporters want Mars to be a backup for humanity, a colony will need enough shielding to get the radiation risk down to low levels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/28/2016 08:53 PM
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.  I've read "but displays are no substitute for a window" with regard to the ITS many times.

A quick google shows that the technology hasn't died yet, but I don't see many offerings that take so many inputs(just 2 for the ones I see at first glance, consumer-facing.)

I don't see why this technology couldn't be improved upon even further than the 9 perspectives, given a forcing function to do so.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 08:55 PM
Deep Blue

I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)

You might not be the only NSF guy with a shark-and-laser aesthetic.   :)

But even without the sharks, yeah.  And you realize the sky overhead would be blue, as seen from within? 

(http://thumbs.dreamstime.com/t/closeup-view-metal-structure-dome-clear-glass-roof-blue-sky-fragment-background-54227629.jpg)

Plus, even under 5 m of water you could get 60% light transmission:  enough for 3 harvests each summer, maybe (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1524017#msg1524017).
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 10:51 PM
It might have to be ice so it wouldn't boil if exposed to martian atmosphere
In this case I was thinking room temperature because it is acting as a buffer to keep temperature stable, so it would have to be inside your pressurised volume. I was thinking you might have fish in it, or use it for swimming also. I think a big swimming pool would be a great addition to a habitat. A hundred meters is a small area to walk in but a large area to swim in.

At the most extravagant it could be a level above your entire habitat. At the least extravagant it could be pools above your homes.

Im not sure to what extent just having a body of water solves the expansion and contraction problem. Biosphere 1 had bodies of water but still had this issue. Fountains might help keep air and water temperatures in sync?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 11:09 PM
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
I was talking only of acute effects, which we have the best evidence of. I'm specifically referring to solar flares, which if shielded by Mars' atmosphere have a negligible impact on total dose and thus REID. So what you're talking about is irrelevant to my point: that Mars' atmosphere tames solar flares.

You're left with GCR and secondaries from that, but that is a different discussion and is not what I was talking about.

Again, solar flares are essentially stopped (for our purposes) by the Martian atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/29/2016 02:56 AM
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
I was talking only of acute effects, which we have the best evidence of. I'm specifically referring to solar flares, which if shielded by Mars' atmosphere have a negligible impact on total dose and thus REID. So what you're talking about is irrelevant to my point: that Mars' atmosphere tames solar flares.

You're left with GCR and secondaries from that, but that is a different discussion and is not what I was talking about.

Again, solar flares are essentially stopped (for our purposes) by the Martian atmosphere.

I was looking for a supporting study, not a repetition.

A 100+ MeV proton will penetrate the martian atmosphere, whether it's a solar flare proton or a galactic proton.  We shouldn't expect one to be "tamed" like a kitten, while the other rips through flesh like a lion.  The assertion doesn't make sense to me.

Also, an unspecified acute radiation symptom is not a lifetime REID 3% statistic.  REID stats are in common use at NASA.  Consider those stats when thinking about solar flares, and Mars radiation risk generally.  Shielding on long-duration Mars habs must be designed to protect for a lifetime.

And -- just to make sure -- you're not thinking of low-energy solar wind protons or solar storm protons, are you, Robotbeat?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/29/2016 02:32 PM
Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/29/2016 03:59 PM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/30/2016 10:40 AM
What habitat building parts and equipment should the first few ITS flights carry?

So far, some of us talked about inflatables or other kinds of more or less pre-fabricated habitats, while others talked of constructed habitats such as tunnels, ice caves and transparent domes.

We talked a little bit about what equipment should be on the manifest for the first flights (e.g. tunnel boring machines) but I feel there's more to it. What would your manifest strategy be for the early flights, so that your vision of an amazing habitat could be realized?
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/30/2016 11:56 AM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/30/2016 02:55 PM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?
Look at the graph an link I posted earlier.

Also, I you want to be precise, flares/storms is not the technical term used. Solar particle events is the term used. And again, look at the diagram I attached and the link I posted above.

Mars' atmosphere does indeed attenuate solar particle events to levels where you don't need to be concerned with them. That was my original claim (reworded to use slightly more technical language), and I was defending that, not making claims about GCR in that statement. Also, micrometeorites also by a concern.

I'm bringing those up because people keep mentioning solar particle events and meteorites as relevant to habitat design, but they aren't unless you build at high altitude (i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mmeijeri on 10/30/2016 03:11 PM
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/30/2016 05:58 PM
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
It takes MUCH more propellant to land on Mount Olympus. I'm still talking about ITS-style EDL. If you want to land on the top of Mt. OLympus, you basically have to do the entire landing propulsively, like landing while moving at Mach 8, versus Mach 3 for supersonic retropropulsion. That's a huge difference and means far less landed mass for a given propellant.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/30/2016 09:47 PM
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
It takes MUCH more propellant to land on Mount Olympus. I'm still talking about ITS-style EDL. If you want to land on the top of Mt. OLympus, you basically have to do the entire landing propulsively, like landing while moving at Mach 8, versus Mach 3 for supersonic retropropulsion. That's a huge difference and means far less landed mass for a given propellant.

Could a lifting body vehicle (not ITS) decelerate aerodynamically in the lower atmosphere with a high drag angle of attack and then gain altitude with a high lift/low drag attitude to land propulsively at high altitudes without burning too much propellant? Or is this too nutty to even contemplate?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/30/2016 11:24 PM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/31/2016 12:02 AM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)

That would depend upon the frequency and duration of the solar flares (of which I am completely ignorant).  If on Mars surface they are completely random, once a month-ish events, with only 15 minutes of warning, and they last for several hours, I'd want all habitats to be 'flare-proof' for their inhabitants.  If on the other hand, they are once a decade event, with hours of notice, and last only 30 minutes, I don't think it would make sense to drastically increase the cost and complexity of the habitats (and decrease their aesthetics and 'livability', such as burying everyone under meters of opaque regolith). In this case I think an adequate 'storm shelter' would make the most sense.

Which of these two extremes best characterizes the flares?

(And again, I acknowledge this completely ignores the GCR issue.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:56 AM
View from inside a Martian dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 01:04 AM
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare
It sure does.

Quote
And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?
You missed the point. The Martian atmosphere is a better shield than that 11cm of aluminum would be. No shielding is necessary on Mars (unless you're at high altitude) for solar particle events. It's not something to bother considering in your habitat design.

GCR might be (though that's actually debatable), but that's about limiting your total time, not about being "caught out" during a solar particle event.

EDIT:And of course I'm not talking about the relatively slow particles in the solar wind.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/31/2016 05:44 AM
Staying Alive, with Aesthetics

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)

That would depend upon the frequency and duration of the solar flares (of which I am completely ignorant).  If on Mars surface they are completely random, once a month-ish events, with only 15 minutes of warning, and they last for several hours, I'd want all habitats to be 'flare-proof' for their inhabitants.  If on the other hand, they are once a decade event, with hours of notice, and last only 30 minutes, I don't think it would make sense to drastically increase the cost and complexity of the habitats (and decrease their aesthetics and 'livability', such as burying everyone under meters of opaque regolith). In this case I think an adequate 'storm shelter' would make the most sense.

Which of these two extremes best characterizes the flares?

(And again, I acknowledge this completely ignores the GCR issue.)

Actually I don't know that shielding has to force a "dramatic increase in cost and complexity" of habitats.  Not on Mars, anyway.  Now in flight, mass is precious and shielding is measured by the centimeter in every dimension, with some complexity.  On Mars however, shielding is readily available and essentially free.  Just fill the space, by any means.  It would be dirty work, but all potentially external to the habitat, and therefore not necessarily requiring an increase in habitat cost or complexity.

And I think that shielding work is required, if Mars habitats are going to house multi-synod crews or permanent settlers, and not just single-synod visitors.  Consider for example McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1):  "Crew Radiation Exposure Estimates from GCR and SPE Environments During a Hypothetical Mars Mission".  The study long and short:  female crew members under 40 approach their lifetime 3% risk limit, even on a single-synod mission with 500-day stay.  That's at -7000 m elevation, beneath 15 cm of aluminum shielding. 

Add also the extra risk of poorly-understood HZE particle effects (http://forum.nasaspaceflight.com/index.php?topic=41526.msg1604544#msg1604544), and it's quite possible that most crew members will approach the 3% limit.  Inference being, most crew members would be restricted to one single-synod mission (500 days on the surface).  A two-synod mission (1300 days on the surface) would put all well beyond the 3% limit.

And come to think of it, if those crew members had cis-lunar experience, or any mission experience beyond LEO, their cumulative prior dosage could use up their "margin", and disqualify them for any Mars mission at all. 

Moreover flare events aren't the worst of it.  In the study, GCR doses are 7-18x as great as flare doses, depending on elevation.  (GCRs with nasty HZE wildcards.)   So to win more time on the surface, the crew would need to slash GCR exposure drastically, day-in, day-out.  Flare shelters wouldn't do the job.  They'd have to lay on the hab shielding.

I think.



Each Lake Matthew dome has a notional 5 m water/ice shield.   That seemed... adequate.  ( ? )  That shield would admit ~60% of incident light, at least in summer.  With blue skies.  In winter the ice would capture only a little light.  Reading light, I guess.   

Question:  Could such shielding give adequate "aesthetics and livability"?  Or what aesthetic goals would you prefer to shoot for?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 10:52 AM
A busy day at Mars Alpha. A few synods after the first flights.

The mostly underground base (not quite a city yet) has just received a new influx of colonists. 
The solar panel farm is just outside the frame of the pictures.  A glacier a few km away provides the water for the base and fuel production.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 11:00 AM
Close up of the ITS-SS.
Title: Re: Envisioning Amazing Martian Habitats
Post by: The Amazing Catstronaut on 10/31/2016 11:43 AM
Gorgeous rendering - and possibly quite realistic.

How ballistics resistant/anchored/thermally/vibro resistant would the dome have to be without being prohibitive, to situate the domes closer to the landing zone? There isn't a distance problem as-is; you're going to need good rover capacity anyway.

The domes would be much easier to construct if they were manufactured with local glass. Perhaps with additives brought from earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 12:20 PM
The plastic PVB layer used in safety glass could be made on Mars from the air and water. It needs H, CO, ethanol, ethylene and propylene (both made from methane), and ascetic acid. There are fancy ways of making ethanol and ascetic acid using catalysts and electrolysis.

You could make the plastic layer extra thick for strength, thermal insulation, toughness, and even some residual radiation shielding (although it'd have to be very thick, like a foot or a meter or so, to make any significant difference in radiation shielding). The thin glass layers could be shipped (carefully!) from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:21 PM
Gorgeous rendering - and possibly quite realistic.

How ballistics resistant/anchored/thermally/vibro resistant would the dome have to be without being prohibitive, to situate the domes closer to the landing zone? There isn't a distance problem as-is; you're going to need good rover capacity anyway.

The domes would be much easier to construct if they were manufactured with local glass. Perhaps with additives brought from earth.
The location illustrated is supposed to be the edge of a volcanic plateau, or the edge of a crater where the rock was properly mixed and melted.  Ideally the rock would need to be hard, but not too hard, so less SiO2, if possible.  If the base could be located near a SiO2 source, ideally sand, to reduce mining energy, that would help with local production of glass.  Hematite spheres could provide iron, but removing the Oxygen would be energy intensive, perhaps there are enough nickel iron asteroids on the surface to provide revenue for roving miners?
I expect the main structural design requirement will be anchoring of the domes due to atmospheric pressure.  Other forces should be minor.  As the ships land pretty much empty of fuel, landing may not be that much of a vibration source.  Take off requires a lot more power, and there is the risk of fuel explosion, so I put the take off pad a bit further away.  There would be a need for some kind of crawler from one pad to the other, perhaps a multiwheel vehicle rather than a caterpillar type vehicle?
I have no idea what is the sound power from a landing, so some of the design elements for airports may not apply.  In the present design I just eyeballed distances based on airports that I have seen over the years.  The underground structure comes from subway projects I have been involved with.  It's basically a big subway station ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 12:40 PM
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:53 PM
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
As a transportation infrastructure, I expect a surface road and rovers is less expensive than a tunnel.  The pad won't be used all that much after all, so low traffic.  The pads might be further away, but then they wouldn't fit into the illustration any more.  A little artistic licence there, perhaps. At least I'm not landing Petawatt class spaceships in the middle of cities with km tall towers ;-) 
Title: Re: Envisioning Amazing Martian Habitats
Post by: kenny008 on 10/31/2016 01:04 PM
Might be best to just put the landing pads "around the corner" from the domes.  The domes would be shielded from direct impact from landing / launch debris by an intervening hill, yet still within a reasonable distance.  No real reason for the domes to face directly at the launch site.  Just drive the rovers from the domes, around the corner of the hill, and out to the launch site.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 01:39 PM
Might be best to just put the landing pads "around the corner" from the domes.  The domes would be shielded from direct impact from landing / launch debris by an intervening hill, yet still within a reasonable distance.  No real reason for the domes to face directly at the launch site.  Just drive the rovers from the domes, around the corner of the hill, and out to the launch site.
Would be fun to see the ships land though, I expect it would be quite an event.  There shouldn't be any debris from a normal landing.  A crash might be another matter though, wouldn't want to compound a catastrophe.  If the vehicle has little fuel and is down to a few hundred m/s, will it be a kaboom or a crumple?
Title: Re: Envisioning Amazing Martian Habitats
Post by: kenny008 on 10/31/2016 02:22 PM
Even well-engineered concrete may pretty quickly degrade after a few landings.  Even LZ-1 showed a little damage from the first landing.  I probably wouldn't want to risk a chunk of pad material being flung through my dome.
But yeah, it would look really cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 02:31 PM
Even well-engineered concrete may pretty quickly degrade after a few landings.  Even LZ-1 showed a little damage from the first landing.  I probably wouldn't want to risk a chunk of pad material being flung through my dome.
But yeah, it would look really cool.
Could there be a layer of water added to the pad just before a landing?  How quickly would it sublimate, or would it turn to ice and add the danger of flying ice blocks to the danger of flying concrete bits?

If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 10/31/2016 02:45 PM
If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.

Hide the domes from the landing field. Only a utility entrance needs to face the pads.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 03:05 PM
If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.

Hide the domes from the landing field. Only a utility entrance needs to face the pads.
Don't forget, these are the Amazing Martian Habitats.  Got to stretch the limits a little.  It should feel and look impressive, but be reasonably safe.  What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?  There are a lot of safe angles, and the domes are 500 m away in the illustration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 12:54 AM
My new ellipsoid version of the domes.

Simpler to build.  Less risk.  Now needs an inside, unless someone convinces me these don't look good or will not work  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/01/2016 01:09 AM
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 01:22 AM
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
ok I'll find some new land
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/01/2016 02:29 AM
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
I think the Martian atmosphere will stop that. But even on Earth, you wouldn't want to be just 600 feet from a landing spaceship of that size! More like several kilometers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/01/2016 04:06 AM
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.

Good idea. At 0.38g the debris from a crash / explosion could fly a long way, damaging domes and scouring roads. With the labour constraint and the perpetual need for physical growth on Mars, it will be important to avoid the "broken window fallacy" over there. Here on Earth, we count selling cigarettes and the treatment of the ensuing cancers as economic growth. We're big enough to hide all this mess here, but the physical economy of Mars will not be forgiving of our mistakes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/01/2016 04:22 AM
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
As a transportation infrastructure, I expect a surface road and rovers is less expensive than a tunnel.  The pad won't be used all that much after all, so low traffic.  The pads might be further away, but then they wouldn't fit into the illustration any more.  A little artistic licence there, perhaps. At least I'm not landing Petawatt class spaceships in the middle of cities with km tall towers ;-)

One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all. So if the tunneling machines will be there in abundance and kept busy at all times, their constant use will lead to improvements in their technology.

Also, relative costs of road making vs tunneling here on Earth, where roads are 1000 times more common than tunnels, might be very different on Mars where the surface is a pretty hostile place that is expensive to work in/on.

The attractiveness of tunnels on Mars has a network effect to it, making tunnels on Mars far more valuable than tunnels on Earth. Every additional kilometer of tunnel is another kilometer of pressurized, earth-like environment added to the base. So Mars will be the planet of the tunnels (not the canals, after all)

Relative notions of value that we are familiar with here won't necessarily apply there. At a distance of 10 to 20 light minutes, the price/cost of a product or service on Mars will depend on the Martian economy which is going to have different priorities than the Earth's economy. Things that are expensive on Earth might be cheap on Mars and vice versa depending on the different relative scarcity of each thing on each planet.

To see that point, consider that if there is no Martian economy but instead we bring everything from Earth, then everything you already have emplaced on Mars is "low cost" relative to everything you don't have which would be astronomically expensive. That's why the Apollo 13 astronauts used socks, plastic bags, suit hoses, the cover from the flight manual and bungee cords to connect a square carbon dioxide scrubber to a round hole in their emergency: those items were the only economical items available to them. Everything else that wasn't already there had an astronomical delivery cost and was therefore eliminated from consideration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 07:12 AM
One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all.

If their energy supply is twice what is needed for fuel production, it will be energy-rich indeed.

They may be somewhat limited over night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 08:26 AM
One or two really big domes, well engineered, it is possible. One for a big stadium where a large crowd can gather and one as a kind of nature park with large trees and animals would be good to have and help make this feel like a home worth working for and living in.

Maybe Martians will not feel the need for a nature park like this but I think they will.

Such structures would come later in the development of the settlement, when most of the materials can be sourced locally. But 10 or 20m domes can be transported. At least a few of them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 08:41 AM
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 01:14 PM
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..

OK, I think it happened while I posted. It caused me some temporary disorientation.  ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 03:12 PM
I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 11/01/2016 03:20 PM
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.

A voice of sanity.
Millions of people spend weeks or even months on end with no outside view through windows. Tens, maybe hundreds of millions of people have rather crappy scene viewable from their home/office windows (such as a wall of the next building filling the entire view).
This is an invented problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/01/2016 03:33 PM
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/01/2016 03:50 PM
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.

Some people prefer a challenge and money, risk and comfort aren't as important to them as the idea of going where no one else has ever gone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ch1le on 11/01/2016 04:07 PM
LaMontage.

Can you give me the sketchup link? I might put my vizualisation skills to use and make some renderings. Finally a chance to contribute to this forum.
Best wishes,
M.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 05:22 PM
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 05:55 PM
I put a bit of structure inside the dome.
btw, elipsoid7 is my favorite. This is how I imagine it, with tiers, and a mall-like atrium in the center.

You could have more wide spaces in the top half, because that inward curving wall is hard to stand up close to. It is actually a bother for normal structures. At least it can give you a wide open sense of space. It is the lower half that is easy to stand next to, so you can divide that up into floors with the wall forming expansive windows. I imagine that area a bit like living in an airport: mall-like, but with wide window-walls looking out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 06:06 PM
This was a bit off topic in the other thread, but I also like the idea of a cellular approach to surface dwellings, if you go that way: https://en.wikipedia.org/wiki/Honeycomb_(geometry)#Space-filling_polyhedra

This would
*allow your bases to grow organically,
*allow construction with uniform components
*allow redundant levels of safety from decompression
*allow repairs and additions without inconveniencing other cells.

You could create interesting varied internal volumes by removing some adjacent faces.
Outer faces could be outward curving, or flat if reenforced with internal cabling. Inner walls could be flat and reinforced with cables for both directions, or curved and designed to be sufficiently strong whether relying on tensile or compression strength.

Longer term I imagine living underground, but these surface areas could be your vertical farms and your parks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 07:36 PM
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/01/2016 10:48 PM
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 11:02 PM
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.
Ok: it linked to this: https://en.wikipedia.org/wiki/Head_(vessel)
"Vessel dished ends are mostly used in storage or pressure vessels in industry. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere (which is the ideal form for pressure containments) while requiring only a slightly thicker wall."

..so it is suboptimal, but apparently only a bit. Im surprised. Does this rely on any 'unbendiness' of the walls? Would these maintain their shape if infinitly strong in tensile strength but fully flexible?.. I think I can see that is true now by imagining constant length chords across the dome. Tensile strength requirements go up, approaching infinity as they approach flatness, but it is not about bendiness (I really should look up the technical term for that :) )
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:21 PM
Here is a view of safebase.  With a nice mountain just at the right place.  The landscape is from South Tunisia.
I've added a solar array field to the view.  IF you want, you can imagine an underground nuclear reactor, or not.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:29 PM
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:37 PM
LaMontage.

Can you give me the sketchup link? I might put my vizualisation skills to use and make some renderings. Finally a chance to contribute to this forum.
Best wishes,
M.
Go to the Trimble 3D warehouse and look for ITS Mars Base.
Dome, vehicle, ITS and a hidden astronaut :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/02/2016 01:47 AM
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread? My thinking is that this thread went public with descriptions and pictures of glass domes and tunnels before Elon Musk mentioned them for the first time ever in his AMA. Also everything about geodesic glass domes on Mars is amazing so the entire other thread would be right at home in here. It would certainly make everyone's life easier to have one thread instead of two, we have enough worries each day to also have to worry where to post ideas about amazing glass domes in Mars Base Alpha.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/02/2016 02:28 AM
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 03:46 AM
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/02/2016 04:00 AM
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

Seems it would be straight forward to have a rollout flexible cover that could cover the glass at night or during dust storms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 04:33 AM
Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/02/2016 04:42 AM
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".
I would prefer them kept separate.. The domes one is about some very specific issues with domes. It is specific enough that it might actually feel answered shortly, and then that thread will fade away while this thread may continue, perhaps now focusing more on the domes and droids and tunnelling aspects.

The thing about that dome thread was specifically issues like anchoring and leaking that made the Dome statement strange to me. Someone did some math about anchoring i havent got around to yet. My expectation is that it is more time, effort and resources for a less trusty and less general result, restricting you to only certain types of ground that may or may not be near the resources you want.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 05:02 AM
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/02/2016 10:03 AM
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".

Our topic is amazing habitats of all kinds and the equipment you would take to build them. Musk mentioned domes together with "tunelling/mining droids" so there is a lot of room for envisioning either in the direction SpaceX seems to be going or in any other direction that seems amazing to you.

I would prefer them kept separate.. The domes one is about some very specific issues with domes. It is specific enough that it might actually feel answered shortly (..snip..)

The thing about that dome thread was specifically issues like anchoring and leaking that made the Dome statement strange to me. Someone did some math about anchoring i havent got around to yet. My expectation is that it is more time, effort and resources for a less trusty and less general result, restricting you to only certain types of ground that may or may not be near the resources you want.

I still think it's better to merge them but it's a step forward for our posters to have clarity on the topic of the other thread. It sounds like it's for extended discussions on glass dome issues around anchoring and leaking.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:27 AM
Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
You're missing the convective term on the outer surface of your glass.  In a typical building insulation calculation, you will have the internal film coefficient, the insulation of the building wall composition, then the outside film coefficient, usually equivalent to R 0.1.  However, if you analyse this film coefficient in detail, you will find that it is an expression of the convective conduction from the mass flow of the air on the surface of the building. Q=hAdT where h is a factor of the mass flow.  Using a slightly different equation, Q=mf*Cp*dT, power=mass flow x specific heat x temperature difference, on Mars with the atmosphere 100 times less dense than on Earth, the mass flow will be 100 times less, so the heat transfer film coefficient will be 100 times higher, or about R10 (imperial units) or 2 inches of styrofoam equivalent.  Now if you have double pane glass, you will have 2 more film coefficient, one on the inside and another on the outside of the second pane.  So the overall R will be practically 30.  Therefore the surface temperature of the outer glass pane will be near to the environment temperature, and the radiation will be very low.
And to further reduce heat low you can put the low emissivity film of the inside of the outer glass pane.  This film is an infrared mirror, so the radiation from the inner glass plane gets reflected, and the radiative heat gain on the outer glass pane is almost nil.  Summing up the very low convection and the very low radiation, you get very low heat transfer, about 1000 times less than your first order estimate, or about 100 kW.  For 12 hours of night then about 1200 kWh of heat loss.  As the heat gain is higher, the domes will tend to overheat, if the solar heat gain is not reduced.  So curtains during the day, and not during the night!

The reason low-e windows are not that effective is that they have an atmospheric pressure gas in the void.  If you had a Mars pressure gas in the void, they would insulate as well as, or better, than the walls.  Of course, they would implode first ;-)


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:34 AM
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:51 AM
A bit of mining.
Anyone had a look a the Hard Rock Miner's handbook I posted a while ago?
Anyway, a typical 2500 Tonne per day gold mine requires 6 MW electrical, plus about 1/2 of that at the mine itself, as fuel and explosives.  This is to crush rock into a very fine powder, to get the gold out, and to dig into very hard rock, usually with high silicate content.  If we just break the rock into gravel, we can use much less power, let's guess 1 kW/tonne.
Since rock has a density of about 3 tonnes per m3, 1 MW of solar power will extract 300 m3 of rock per day, using standard mining methods.  Over a year, we should be able to create 300x300 = 90 000 m3 of underground volume. 
If we divide this into 4.5 m floors, then we have 20 000 square m of living area, or enough for 1000 people at 20 m2 per person.  In two years, about 40m2 per person.
If someone could check this I would really appreciate it, but I guess i'll start right away on illustrating a few big caves....


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/02/2016 11:07 AM
Very good calculations, lamontagne!
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 12:21 PM
Dome Heat

Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
You're missing the convective term on the outer surface of your glass.  In a typical building insulation calculation, you will have the internal film coefficient, the insulation of the building wall composition, then the outside film coefficient, usually equivalent to R 0.1.  However, if you analyse this film coefficient in detail, you will find that it is an expression of the convective conduction from the mass flow of the air on the surface of the building. Q=hAdT where h is a factor of the mass flow.  Using a slightly different equation, Q=mf*Cp*dT, power=mass flow x specific heat x temperature difference, on Mars with the atmosphere 100 times less dense than on Earth, the mass flow will be 100 times less, so the heat transfer film coefficient will be 100 times higher, or about R10 (imperial units) or 2 inches of styrofoam equivalent.  Now if you have double pane glass, you will have 2 more film coefficient, one on the inside and another on the outside of the second pane.  So the overall R will be practically 30.  Therefore the surface temperature of the outer glass pane will be near to the environment temperature, and the radiation will be very low.
And to further reduce heat low you can put the low emissivity film of the inside of the outer glass pane.  This film is an infrared mirror, so the radiation from the inner glass plane gets reflected, and the radiative heat gain on the outer glass pane is almost nil.  Summing up the very low convection and the very low radiation, you get very low heat transfer, about 1000 times less than your first order estimate, or about 100 kW.  For 12 hours of night then about 1200 kWh of heat loss.  As the heat gain is higher, the domes will tend to overheat, if the solar heat gain is not reduced.  So curtains during the day, and not during the night!

The reason low-e windows are not that effective is that they have an atmospheric pressure gas in the void.  If you had a Mars pressure gas in the void, they would insulate as well as, or better, than the walls.  Of course, they would implode first ;-)

Thanks for the numbers there.  It looks like I was wrong in thinking that because a glass pane insulates very poorly, convection off the pane should be low even at 1 atm. 

As an apples-to-apples cross-check, can you calculate the simple 150-m dome's heat loss your way?  That is, the dome without the improvements of double-panes and low-e film.  If you could calculate that heat loss under 1 kPa atmosphere and under 100 kPa atmosphere, those would be good cross-check reference points.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 12:54 PM
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.

Isn't the brittle transition temperature more critical?  Both low- and high-density polyethylene transition at -70 C (http://omnexus.specialchem.com/polymer-properties/properties/ductile-brittle-transition-temperature).

And how might an algae grow tube maintain the ~10 C growth temperature range, while radiating and conducting heat out on the surface? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 01:08 PM
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.

Isn't the brittle transition temperature more critical?  Both low- and high-density polyethylene transition at -70 C (http://omnexus.specialchem.com/polymer-properties/properties/ductile-brittle-transition-temperature).

And how might an algae grow tube maintain the ~10 C growth temperature range, while radiating and conducting heat out on the surface?
Good points, it was notional and not calculated. I'll add this to the response to your earlier question about domes, since the tubes are long skinny domes.  Regarding HDPE, I believe one of the reasons that rovers have metal wheels is that NASA has been incapable of finding a material that remains flexible at all possible temperatures.  So HDPE might fail as you mention. Certainly rubber does.  A very incomplete answer might be that colonists would deploy the algae tubes in summer, when the air is relatively warm, then use redundant heating systems for the tubes.  If the water freezes the tubes will be finished anyway.  Then they would need to store enough food for the required repair/replacement time.
If the base was nuclear powered, then there should be a lot of waste heat to keep the tubes from freezing, but that's another thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/02/2016 01:40 PM
Isn't the brittle transition temperature more critical?
...

Only when toughness is in question, i.e. when under impact. Brittle does not mean "weak", it simply means the material is not ductile. Concrete and granite are brittle materials.

Polycarbonate, for example, is MUCH STRONGER at 4K than it is a room temperature, even though it's not nearly as tough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/02/2016 09:23 PM
I still think it's better to merge them but it's a step forward for our posters to have clarity on the topic of the other thread. It sounds like it's for extended discussions on glass dome issues around anchoring and leaking.
There is also cross linking to other posts. I actually like threads that end. I hate threads that go on for a hundred pages where the good stuff gets buried, and then the topic gets rehashed again. Rehashing can be irritating, being told you are rehashing and this was all covered 100 pages back, and "didn't you read it??" is also irritating :)

OFF TOPIC:
I just had what I think is an AWESOME idea. Imagine if some threads were simply impossible to post to more than once? But you can reedit your post as often as you like.

These would become like thesis threads. Everyone has their thesis, whether on radiation, moon vs mars or other pet ideas. Whenever a topic starts up say on radiation again.. rather than repeating arguments over and over, you link to your thesis and just make some comment about the particular relevant part in it, and you polish your thesis in response to comments and counter arguments.

Im convinced that the quality of online discussion is largely shaped by details of forum technology. It is a very interesting topic all of it's own. Currently, it is a jungle out there. Someone could come up with the right idea and it might revolutionise how the human race manages knowledge as significantly as the scientific method did.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 11:37 PM
Here is my calculation of the various domes.

It was a bit more complex than expected, since I needed to convert the external film coefficient into the actual convection coefficient, and then iterate manually  on a continuity formula, where Conduction in glass = Radiation+ external convection.

Anyway.
A 75m radius on Mars gains 16 MWh in a day at 45 degrees north.
For a single pane glass dome and Earth pressure external atmosphere, the loss is 300 MWh per day.
For a single pane glass dome with Martian external pressure, the loss is 73 MWh per day.
For a double pane glass with low emissivity film and a martian pressure air gap, the loss is 7 MWh per day.

So we need the low emissivity film and we need the second glass pane.

Similar results for a plastic film algae growth tunnel. 2mradius 200m long
For a single wall, gain is 750 kWh, loss is 7500 kWh, so perfect as a nuclear reactor cooling system, not so good otherwise.
For a double wall with low E film and a low pressure air gap, the loss is 350 kWh.  So no secondary heating required and the tube in a net energy gain.

These are commuter train time calculations, so there may be errors, take with a grain of salt.  But I think it's probably pretty close to reality.


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 04:54 AM
Toughing It Out

Isn't the brittle transition temperature more critical?
...

Brittle does not mean "weak", it simply means the material is not ductile.

Hence the "brittle/ductile transition". 

Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 05:38 AM
Survive

Here is my calculation of the various domes.

It was a bit more complex than expected, since I needed to convert the external film coefficient into the actual convection coefficient, and then iterate manually  on a continuity formula, where Conduction in glass = Radiation+ external convection.

Anyway.
A 75m radius on Mars gains 16 MWh in a day at 45 degrees north.
For a single pane glass dome and Earth pressure external atmosphere, the loss is 300 MWh per day.
For a single pane glass dome with Martian external pressure, the loss is 73 MWh per day.
For a double pane glass with low emissivity film and a martian pressure air gap, the loss is 7 MWh per day.

So we need the low emissivity film and we need the second glass pane.

Similar results for a plastic film algae growth tunnel. 2mradius 200m long
For a single wall, gain is 750 kWh, loss is 7500 kWh, so perfect as a nuclear reactor cooling system, not so good otherwise.
For a double wall with low E film and a low pressure air gap, the loss is 350 kWh.  So no secondary heating required and the tube in a net energy gain.

These are commuter train time calculations, so there may be errors, take with a grain of salt.  But I think it's probably pretty close to reality.

Thanks for those hard calcs. 

Cross-check:  Setting the dome's single-pane temperature delta to 160 C, under 100 kPa, produces a heat loss roughly consistent with the terrestrial 100 MW flux predicted from R-value.  So that seems right.

Corollary:  That terrestrial heat loss is ~7x your heat loss under 1 kPa, indicating that max heat loss during the martian winter night might be 10-20 MW.  With your several improvements, the max heat loss is cut to about 800 kW.

Energy:  Finding the energy to heat your dome could be challenging, even with the improvements.  Your daily 7 MWh loss = 25 billion J.  And a 100 ton flow battery can deliver, I think, maybe 70 billion J of electrical heating. 

That's 3 nights. 

How to survive the winter?

(http://www.aljazeera.com/mritems/Images/2015/11/30/a3a17370d15d460f805e1150476246a9_18.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/03/2016 08:45 AM
Random thoughts:

A solar tower type set up could generate electricity, and the waste heat from this could also go to heating your dome. This reminds me of an idea I had: to dig into one wall of an east-west canion and having reflectors on the far wall. In that case I thought the reflectors could also be solar panels, only reflecting light most suitable for photosynthesis into the greenhouses to avoid baking them.

Solar panels also have the advantage of working better during dust storms.

The other thought was just that it is probably a lot easier to create a true vacuum layer on Mars? Would that help? Or is most of the leakage in visible light? If that was the case you might want to cover the the dome in white on cold days.. like Christmas :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:40 AM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

The base is mostly underground, with a pair of exterior domes and a large spaceport, as well as a solar power field.  Not illustrated are large underground stores (artificial caverns) of oxygen, methane, nitrogen and water.  At least enough for two years of survival.  Would these be liquid?  Probably, with a bit of insulation.
If there is someone who participated in the food on Mars thread, was there a conclusion?  Algae tubes or underground caves with artificial lighting?

As far as winter goes, there's probably an optimum latitude where winters are less extreme, Mars tropics, if you will.  We need a spot that isn't too cold in winter, and not so hot that all ice has sublimated.  I believe there are quite a few though. 
The typical average solar gain is twice the night loss in the calculations.  So most of the time the dome needs cooling, not heating.  In winter, you might simply close down the domes and live in the underground sections.  Open again in spring, as soon as the domes have positive gain.  As we do on Earth with greenhouses.

Carbontate deposits have been found on Mars, Wikipedia: Carbonates on Mars.  Perhaps that might make it easier to fabricate certain plastics.  There's probably a geology thread on the Forum, somewhere.

In the double pane glass dome, the losses are mostly radiative.  A simple solution is triple pane glass (available on Earth, after all) , but you do start reducing the gain.  Low e films are not perfectly clear on the non mirror side.  Another would be internal movable curtains, used in most greenhouses in Canada, BTW.

The mathematics of Wikipedia: multilayer insulation can be used to analyse the dome' insulation

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 11:33 AM
Toughing It Out

Isn't the brittle transition temperature more critical?
...

Brittle does not mean "weak", it simply means the material is not ductile.

Hence the "brittle/ductile transition". 

Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.
Simply not a concern with multiple panes. Just like with Shuttle, the load bearing pane is different than the outer refractory pane. I just don't see the issue, here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/03/2016 11:51 AM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 11:56 AM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?
SpaceX people, hopefully with the help of others. In ITSes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 11/03/2016 12:08 PM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Exactly the same questions apply to any proposed habitat on Mars. And many of the proposed ones are more complicated that this!
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/03/2016 12:18 PM
...
Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.

Not really. Reduced toughness only matters under impact loads, and the external walls of a hab shouldn't normally see any impact loads. Meteorites energetic enough to break a several centimeter thick polycarbonate panel are quite rare as the atmosphere effectively slows small ones. Flying debris from a spaceship landing/takeoff/RUD is more likely, but should not be a common occurrence (if it is, you have bigger problems).

Designing a pane and frame structure that can survive losing several panes is not that difficult... it's not like losing a few panes will cause the whole habitat to explode. A large dome would take hours to depressurize even if a couple panels are completely gone, giving time to plug even a large leak.

And as Chris notes above, a multi-layer construction is likely for thermal regulation. The outer panes would be designed for thermal regulation and abrasion resistance (probably glass) , and the inner layers would be designed for structure and pressure containment and puncture resistance (probably polycarbonate or a similar polymer). That way the structural members are always at or near inside temperature and can stop anything that comes through the thermal layer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: bregallad on 11/03/2016 12:56 PM
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.

A voice of sanity.
Millions of people spend weeks or even months on end with no outside view through windows. Tens, maybe hundreds of millions of people have rather crappy scene viewable from their home/office windows (such as a wall of the next building filling the entire view).
This is an invented problem.

I don't think it is an invented problem. There's a big difference between not having a great view/not going outside, and knowing you can't EVER go outside. The psychological aspects of this cannot be ignored.

But one technology I think could help with this, in small and large underground bases:

https://www.youtube.com/watch?v=aJ4TJ4-kkDw

If you combine these skylights in a large underground dome with plants etc. it could look and feel like outside without the complexity of an actual glass dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 01:13 PM
You can go outside on Mars just as much as you can in Minnesota in January. In both cases, if you're not properly dressed, you'll be dead in minutes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: bregallad on 11/03/2016 01:21 PM
You can go outside on Mars just as much as you can in Minnesota in January. In both cases, if you're not properly dressed, you'll be dead in minutes.

Imagine this: You live in a tunnel with no windows. It's small, and ugly (designed for utility not style, like nuclear bunkers if you've ever seen them). You can't go outside unless you take at least one hour to put on a suit, go through stringent procedures, and then there is still the risk of something going wrong at all times, and that could be fatal.

Now imagine living in Minnesota. Were you have big windows, where you can see the outside. You can run outside in your shorts if you really want to. If you do end up outside with little clothes you can seek help. You have a heated vehicle that can take you to see other people... etc.

There is no equivalency here. It is a completely different situation, let's not pretend it is not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 01:24 PM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.  And they didn't build a 10 000 people complex but a 1 billion $ mine infrastructure, including removal of the overburden and a crushing facility for 40 000 tonnes of ore per day, and housing for 400-1000 permanent workers.  Then then took the construction camps apart.

The cost of a 400 people camp on Earth is about 250 000$ per unit so about 100 million dollars.  My wild guess would then be about 2 billion dollars, with infrastructure, excluding transportation costs.  so about 200 000 dollars per colonist.  Not houses, but small apartments.

Transportation and power costs are wildly dependant on the possibilities of in situ resource development.  I will refrain from over speculating on that subject, if you will allow. Constructive suggestion would be nice, however ;-)  I'm certainly willing to improve the proposed arrangements.

Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/03/2016 02:22 PM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.  And they didn't build a 10 000 people complex but a 1 billion $ mine infrastructure, including removal of the overburden and a crushing facility for 40 000 tonnes of ore per day, and housing for 400-1000 permanent workers.  Then then took the construction camps apart.

The cost of a 400 people camp on Earth is about 250 000$ per unit so about 100 million dollars.  My wild guess would then be about 2 billion dollars, with infrastructure, excluding transportation costs.  so about 200 000 dollars per colonist.  Not houses, but small apartments.

Transportation and power costs are wildly dependant on the possibilities of in situ resource development.  I will refrain from over speculating on that subject, if you will allow. Constructive suggestion would be nice, however ;-)  I'm certainly willing to improve the proposed arrangements.

As there's likely to be some injuries or worse, plus NASA would want to send along a few scientists, and construction in a near vacuum is a bit different, you'd probably need to bump up the personnel count by about at least 25%, but overall, not an entirely unreasonable estimate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 02:59 PM

As there's likely to be some injuries or worse, plus NASA would want to send along a few scientists, and construction in a near vacuum is a bit different, you'd probably need to bump up the personnel count by about at least 25%, but overall, not an entirely unreasonable estimate.
Injuries are rarer than they were.  The projects I was involved with all had 0 loss of life.  There would have been hell to pay if someone had died from work related injuries.  Probably going to kill a few robots, though.  and depending on colonist involvement you might have some deaths from enthusiastic amateurs.
I'm willing to admit 25% more at this point, no problem.  you guess is a good as mine.  Likely better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 08:39 PM
Connery & Vacuum Exposure

A large dome would take hours to depressurize even if a couple panels are completely gone, giving time to plug even a large leak.

Actually, if lamontagne's 150 m dome lost one brittle panel it would depressurize to the Armstrong Limit in ~2 minutes (http://www.geoffreylandis.com/higgins.html).  (If 60 kPa dome and 35 m2 panel.) 

Approx. illustration, with Connery:

https://www.youtube.com/watch?v=vyzGCAJngkc

Golf clap for Connery.

You might be thinking of small constrained punctures, more typical of tear-resistant ETFE foil, for example.  Tear resistance is an important property of ETFE, but ETFE foil lacks the optical excellence of glass. 

Question:  Are there any cryogenic foils that feature both high tear resistance and also glass-quality transmission, haze and clarity (http://www.byk.com/fileadmin/byk/support/instruments/theory/appearance/en/Intro_Transparency.pdf) (ASTM D1003 test)?  Such a foil, if it existed, would have many potential uses in a Mars hab.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:11 PM

Actually, if lamontagne's 150 m dome lost one brittle panel it would depressurize to the Armstrong Limit in ~2 minutes (http://www.geoffreylandis.com/higgins.html).  (If 60 kPa dome and 35 m2 panel.) 


Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Anyway, here is a handy spreadsheet with a hole and pressure drop calculator.  You can size at will.
For a 1m pane, the pressure drop would be 60% after 30 minutes, down to 30 kPa.  Severe but manageable IMHO.

And here is a view of the base without the ground.  I've added a fresh water and waste water caverns, a liquid oxygen cavern, a nitrogen cavern and a methane cavern.  The nitrogen is arbitrarily sized for 5 refills of the habitat.



Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 10:20 PM
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!  (Also bending force is, I think, typically concentrated in the frame, not the panes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:34 PM
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!
Sorry to have mislead you.  The illustration was just nominal and indicative. Concept art, not engineering drawings.  Making all the little windows would take too much time to render,  so I made them bigger.  Just imagine them at a size you feel is reasonable.  Personally, that's 1 m2 max.  35 m2 will get all the ''tv screen are more practical and just as pretty as windows'' people onto my back, I'm afraid ;-)
I haven't illustrated a true geodesic dome either, just in case.  It's more of a Victorian greenhouse dome. It would take me days to build a model of a geodesic dome at this scale.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/03/2016 11:10 PM
The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.

Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/04/2016 12:00 AM
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Back of the envelope cost comparisons of earthworks vs. "marsworks" will probably give wrong answers. There are (at least) two reasons for this.

The first reason is that on Mars, opportunity costs are relative to your opportunities on Mars, and the costs to bring hardware over have already been sunk and are irrelevant. So the opportunity cost exercise you'd have to do is: for the same time and/or wear and tear of the capital piece of equipment, how much pressurized volume can I create on Mars, and what is the quality of that volume in terms of weighted metrics that I care about? You rank these projects, and the project that has the lowest time or wear and tear cost per (quality-adjusted) unit pressurized volume is the project with the lowest Martian opportunity cost.

The second reason is in some ways a detail aspect of the first one. To make valid inferences for Mars costs from cost information that applies for analog processes on Earth, one must first decompose the Earth cost function to a high level of detail and then a cost function for Mars should be constructed. But before constructing the Martian cost function (in terms of time, wear and tear, etc.) all the explicit AND IMPLICIT assumptions for each line item should be carefully considered to see if the assumptions that apply on Earth also apply to your digging environment on Mars. Once you are sure you have identified and tested all assumptions, then and only then you can build the Martian cost function and plug it into your opportunity cost analysis above.

So the answer to your question, of what it would cost on Earth and how long it would take to complete a similar project here, is that how much it costs on Earth has little bearing to the opportunity costs on Mars. Or to put it another way that is relevant to this thread, the more amazing and the bigger the habitat that can be constructed with a given set of equipment, then all other things being equal, the lower the Martian opportunity cost of building it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/04/2016 12:11 AM
It's almost impossible to accurately estimate the cost of a large Mars project like we're discussing here. Just take logistics. If you took a NASA approach of assuming expendable architecture with half a dozen totally different vehicle designs to achieve the goal with half a dozen new technologies (NTR, etc), the cost would be about 4 orders of magnitude greater for a given large capability than SpaceX's approach (which some are skeptical of).

As such, there's no chance of accurately comparing Mars vs Earth costs, except to say Mars will cost more. How much more could easily vary by a factor of a thousand depending on who you ask.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/04/2016 12:17 AM
Agreed, it's almost impossible. Notice how I carefully and completely avoided reference to dollars or any units of Earth money. That was not by accident, on Mars the only costs are opportunity costs and the only way you can measure those is relative to the opportunities you pass up to do the activity whose cost is in question.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/04/2016 03:48 AM
Pharaohs of Mars

I've added a fresh water and waste water caverns, a liquid oxygen cavern, a nitrogen cavern and a methane cavern.

These tunnel-bored storage caverns would be amazing.  Like the chambers of the pyramids!   

But, why build them?   

Oli (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603731#msg1603731) suggested the scale of the tunnel-boring challenge, and I tend to think he understated.  One would tunnel only when necessary; when other construction methods are clearly inferior. 

So, these storage caverns:

Caverns in bedrock can hold pressurized gases, but a cryogenic distillery can liquefy gases to increase density hundreds or thousands of times, for storage efficiency.  One such plant is required for CH4 and O2 propellant anyway.  It could just as easily liquefy nitrogen.  Argon too, if, say, you wanted to harvest and store propellant for solar electric propulsion at Mars.

Assuming your selected site had appreciable ice and salts, and some topographic depression, you could make a simple brine pool.  Melt, mix, dump.  Salts lower freezing point and raise boiling point, so that the pool remains liquid at depth over a wide temperature range.  Surface freezing increases salt concentration, depressing the brine's freezing point further.

Place lightweight, cryogenic, insulated inflatables in the brine.  Attach the cryogenic spigots, and fill the inflatables with liquid gases.  The gases are now stored.  Freshwater in a separate brine pool, with heated inflatable.  Wastewater, likewise.  Storage caverns are thereby rendered unnecessary.

Such a scheme might be implemented over a martian summer, saving years of cavern construction work, and the thousands of cargo tons and billions of dollars associated.

Or, why not?

(http://cdn.history.com/sites/2/2014/01/grand-gallery-khufu-P.jpeg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 05:15 AM
The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.

Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 05:28 AM

Assuming your selected site had appreciable ice and salts, and some topographic depression, you could make a simple brine pool.  Melt, mix, dump.  Salts lower freezing point and raise boiling point, so that the pool remains liquid at depth over a wide temperature range.  Surface freezing increases salt concentration, depressing the brine's freezing point further.

Place lightweight, cryogenic, insulated inflatables in the brine.  Attach the cryogenic spigots, and fill the inflatables with liquid gases.  The gases are now stored.  Freshwater in a separate brine pool, with heated inflatable.  Wastewater, likewise.  Storage caverns are thereby rendered unnecessary.

Such a scheme might be implemented over a martian summer, saving years of cavern construction work, and the thousands of cargo tons and billions of dollars associated.

Or, why not?

The storage caverns shown are for liquefied gases.  They are, as you say, thousands of times smaller and do not require many resources beyond conventional mining equipment.
So we agree!

I have no opinion between cut and cover and mining. Both might produce similar results.  The caves illustrated do not need tunnel boring machines, by the way, they are on grade and can be built using drill and blast, if nitrates are cheap enough to produce, or mechanical grinding.  Adequate terrains might produce interesting cut and cover possibilities.  In the end though, they would be very similar to what I'm showing, no?

Brine covered tanks are very interesting.  I expect there are no particular problems with large cryogenic temperature flexible membranes? so it might indeed be a more economical solution.  There would be some additional work required for methane and nitrogen though, since these are quite a bit less dense than water.  Actually, water is less dense than brine, so some form of anchoring or most likely ballasting would be required.  Adding some complexity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 06:41 AM
A large underground excavated cave, for 5000 people.
Perhaps a little ambitious :-) 
400m long and 100m in diameter
80 000 m2 of food production in the lower levels, a  16 000 m2 green park in the middle.
about 25 000 m2 of apartments.  A bit tight, at 50ft only per room. I should add some built area, I think, work and common areas.
The cavern is built rapidly; the apartments are added much more slowly, as population arrives.

Anyone has Amazing architectural styles to suggest?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 06:59 AM
A FIFA sized football field.

A remarkable waste of space, I expect.  But what might be the requirements for sport facilities in a Martian habitat, a few years down the line?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/04/2016 07:04 AM
Mining Methods

I have no opinion between cut and cover and mining. Both might produce similar results.  The caves illustrated do not need tunnel boring machines, by the way, they are on grade and can be built using drill and blast, if nitrates are cheap enough to produce, or mechanical grinding.  Adequate terrains might produce interesting cut and cover possibilities.  In the end though, they would be very similar to what I'm showing, no?

I wouldn't know the pros/cons of tunnel boring vs. drill-and-blast, but neither sounds like an easy time on Mars.  :)  Boring is direct-electrical mechanism, which should be most efficient, but limited in hours of operation, right? 

And did you have some thought on ISRU nitrates or other explosive options for drill-and-blast?  There are a lot of potential redox pairs in the notional facilities:  even the greenhouse could potentially supply.  Thinking specifically of greenhouse nitrate production.  Poster sghill owns an electrochemical fertilizer company with equipment that makes nitrate at ambient air pressure, more efficiently than the standard high-pressure Ostwald process.  It could conceivably be adapted as a greenhouse cottage industry: in-house fertilizer production, with a mining application in your scheme.  Posts 1 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1579832#msg1579832) 2 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1579934#msg1579934) 3 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1583273#msg1583273). 

Why the nitrate preference?  For ease of transport, in ammonium nitrate solid, or some other advantage? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/04/2016 01:00 PM
Liquid oxygen and carbon monoxide mix would be a potent and cheap explosive on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/04/2016 04:03 PM
Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.

Well, you pass the honesty test. :) But I have a hard time envisioning any terrestrial entity willing and able to support hundreds (to say nothing of 10,000) people on Mars for years on end with no payback in prospect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/04/2016 04:22 PM
Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.

Well, you pass the honesty test. :) But I have a hard time envisioning any terrestrial entity willing and able to support hundreds (to say nothing of 10,000) people on Mars for years on end with no payback in prospect.

Depending on how much money we're talking about, a foundation setup by Musk and other billionaires could do it. Not everything has to show a profit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 08:05 PM
Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 08:27 PM
This is how large room and pillar construction can get:

Subtropolis in Kansas city

https://www.youtube.com/watch?v=3DJ4VjIRM24
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/04/2016 08:44 PM
Anyone has Amazing architectural styles to suggest?

I like the principles of city design as described at http://www.carfree.com/ The site is looking kinda dated now but if you take the idea of the districts and apply them to individual cavens then there is alot that could be applied to Mars habitats.

Worth a look I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/04/2016 09:18 PM
Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?

Look up Sandvik Roadheader.  Amazing machines. Much more versatile than a TBM for hab cavern excavations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/05/2016 01:55 AM
Boring Basalt

Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?

Look up Sandvik Roadheader.  Amazing machines. Much more versatile than a TBM for hab cavern excavations.

Pretty amazing.  Here's the big Sandvik MT720 in action.

https://www.youtube.com/watch?v=QyE5kAothQ4

I see the MT720 is designed for rock "exceeding 120 MPa uniaxial compressive strength" (UCS).  That sounds like a lot, but igneous rock can have even higher UCS.  In one tunnel boring case study (http://www.sciencedirect.com/science/article/pii/S1674775513001224), basalt in the Deccan traps had a max UCS of 143.  Would that pose problems for the MT720?   

In the study's particular basaltic tunnel, a gripper TBM was used.  For the purpose of opening large crewed facilities in igneous rock, I think gripper TBMs on the scale of these Herrenknecht TBMs might be required.  Look at the scale and complexity, not only of these TBMs, but of the plants supporting them.  Adapting all that to martian conditions, would be, like... whew.

https://www.youtube.com/watch?v=quu2r5vs0hA
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/06/2016 11:36 AM
A large underground excavated cave, for 5000 people.
Perhaps a little ambitious :-) 
400m long and 100m in diameter
80 000 m2 of food production in the lower levels, a  16 000 m2 green park in the middle.
about 25 000 m2 of apartments.  A bit tight, at 50ft only per room. I should add some built area, I think, work and common areas.
The cavern is built rapidly; the apartments are added much more slowly, as population arrives.

Anyone has Amazing architectural styles to suggest?


Venice and Amsterdam mansions on either side of canals, including the canals, boats and gondolas.

Also the magnificent covered galleries in Milan, Vittorio Emmanuele I think? from upthread..

Renaissance-era facades and interiors from Europe.

Each neighborhood to have one style and a name to match - "Little Venice", "Little Milan" etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/06/2016 08:22 PM
The galleries on Eros in the sci-fi series "The Expanse" are pretty cool (fake sky, of course)...

(http://sfmag.hu/wp-content/uploads/2016/02/TheExpanse_gallery1.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/06/2016 11:28 PM
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!  (Also bending force is, I think, typically concentrated in the frame, not the panes.)

For a spherical dome dominated by internal pressure loads there is almost pure tension and no bending anywhere in the structure. The panes should be small enough that losing a few doesn't compromise the structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 12:05 PM
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power
Electrical power, 2400V. 350 kW.
9mx6m tunnel cross section
Remotely operated, automatic profiling of cut.
50 tonnes mass,shipped unassembled
Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

I would expect this to be shipped with the first large group of colonists.


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/07/2016 01:21 PM
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 01:34 PM
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Well, let's find a nice area of sandstone, or something else both soft enough and strong enough.  Mars has varied terrain, we don't need to find the hardest one, but the most appropriate and easiest one.
Here is an outcropping of sandstone on Mars, and a link to a bit of Martian geology.  Could dig into that?

http://geology.com/stories/13/rocks-on-mars/


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/07/2016 05:52 PM
Sharp Cut

Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Well, let's find a nice area of sandstone, or something else both soft enough and strong enough.  Mars has varied terrain, we don't need to find the hardest one, but the most appropriate and easiest one.
Here is an outcropping of sandstone on Mars, and a link to a bit of Martian geology.  Could dig into that?

http://geology.com/stories/13/rocks-on-mars/

An interesting exercise, no matter how you cut it.  :) 

Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?

(https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/PIA19912-MarsCuriosityRover-MountSharp-20151002.jpg/800px-PIA19912-MarsCuriosityRover-MountSharp-20151002.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 07:21 PM

Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?

Perhaps in the sandstone layer, if it is thick enough?  Gypsum is also possible, if I understand the mineralogy, but that might be too fragile.  Gale Crater is perhaps a little close to the equator for important amounts of water?  Perhaps a similar crater, but closer to one of the possible glaciers?  A little to the north?   What would be good is a combination of a nice thick eroded sandstone formation, close to a level floor area and an important glacier.  I take it I can continue designing a base around caves built by a machine such as the roadheader?
Next step: a rolling crane, a shed, a low mining truck and some early habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 11/07/2016 08:51 PM
The significant point about these geodesic domes are that they are constructed from large quantities of small generic parts. Additionally such parts would be candidates for 3D printers to produce from local materials (such as glass from silicon readily available). It would be interesting to have a 3D printer that printed glass panes of a specific shape with edges that have lips to help with sealing. Plus the glass panes or opaque glass panes for the lower levels would represent the major portion of the weight of the "dome".

Unfortunately the structural elements and panes are individually designed to create a dome of a specific diameter even though there are a large number of identical elements they are still specific to a specific dome size.

The answer would be a set of 3D printers that can then print the structural and panes from feed-stock either shipped to Mars or locally made such that the domes are designed at the location based on the conditions found, such as using a specific crater as a starting point for siting the dome but only once the crater has been explored. This method of using shipped feed-stock vs shipping finished elements makes it easier to ship since feed-stock is very compact and has high mass to volume vs end product manufactured elements.

This method has many advantages in that it is from the beginning a drive to make it point to use local resources as much as possible as early as possible. As feed-stock becomes available from local sources that becomes that much less of that feed-stock need from earth which can be swapped for the other feed-stocks that increases the overall increase in the amount of domes created for a given shipping amount.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/07/2016 09:07 PM
Gypsum is a highly hydrated mineral so if you have gypsum you have water. And the energy needed to extract water from gypsum is about 1.5-2 orders of magnitude less than required to electrolyze the water for propellant usage (i.e. Methane--once combined with CO2--and oxygen), and that will be the primary usage of water for a while because you need 2000 tons of propellant per ITS.

So I don't think that being near the equator is a bad thing since you still have access to plenty of water and you have more moderate temperatures and access to better sunlight and an easier time landing and especially launching.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/07/2016 09:08 PM
Hellas basin.
7000m below datum.
Glaciers reported 250m thick.
Don't know about the rocks.
Southern Hemisphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/07/2016 09:13 PM
Hellas is reportedly pretty dusty and is pretty far south. Both are bad if you're reliant on solar power. Melas Chasma in Valles Marineris is -5km still, right on the equator, has lots of hydrated minerals (and even lineae) and a fantastic view.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/07/2016 09:18 PM
Any glaciers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 11/08/2016 01:15 AM
Hellas is reportedly pretty dusty and is pretty far south. Both are bad if you're reliant on solar power. Melas Chasma in Valles Marineris is -5km still, right on the equator, has lots of hydrated minerals (and even lineae) and a fantastic view.

Plus lots of nooks & crannies to isolate a landing field and a nuclear plant from residences.
Burrow into the many hillsides & cliff sides for heavily shielded colonial homes.
Just check for rockslides etc. first
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 01:43 AM
The base domes with a tunnel digger and rolling crane set up in the foreground.
The crane is inside a barely visible plastic dome, that has a low e coating on the inside.  There are radiant heaters on the crane structure.
This allows the roadheader to be made from standard materials, as  it never sees very cold temperatures, since Martian cooling is mainly radiative, not convective. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 02:52 AM
Raw and finished tunnel.
10m wide x 7m high
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 02:57 AM
People are supposed to be living in the glass domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 03:08 AM
People are supposed to be living in the glass domes.
It's just one of the possibilities.  If the glass domes prove too expensive compared to tunnels there will be a mix, with the domes being more of a prestige area, perhaps.  Or people sleeping in the tunnels, and doing daily activities in the domes.   Or if the radiation dosage in the domes at full time gests too high.
The strict glass domes and industrial tunnels is another thread, this one is more free, IMHO.  As long as it's amazing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 03:24 AM
The significant point about these geodesic domes are that they are constructed from large quantities of small generic parts. Additionally such parts would be candidates for 3D printers to produce from local materials (such as glass from silicon readily available). It would be interesting to have a 3D printer that printed glass panes of a specific shape with edges that have lips to help with sealing. Plus the glass panes or opaque glass panes for the lower levels would represent the major portion of the weight of the "dome".

Unfortunately the structural elements and panes are individually designed to create a dome of a specific diameter even though there are a large number of identical elements they are still specific to a specific dome size.

The answer would be a set of 3D printers that can then print the structural and panes from feed-stock either shipped to Mars or locally made such that the domes are designed at the location based on the conditions found, such as using a specific crater as a starting point for siting the dome but only once the crater has been explored. This method of using shipped feed-stock vs shipping finished elements makes it easier to ship since feed-stock is very compact and has high mass to volume vs end product manufactured elements.

This method has many advantages in that it is from the beginning a drive to make it point to use local resources as much as possible as early as possible. As feed-stock becomes available from local sources that becomes that much less of that feed-stock need from earth which can be swapped for the other feed-stocks that increases the overall increase in the amount of domes created for a given shipping amount.
If the domes are made from tubes and connectors, we might only 3D print the connectors and cut the tubes to length.  Probably faster.
It might also be possible to have standard polygonal (or triangular) glass shapes and grind these to fit, following the design of the required pattern to adapt to local conditions.
The earlier domes might be fixed and relatively small.
It would be important to analyse the structure so the failure of a window does not induce too much torsion in the framing, or we might get a zipper effect and a cascade of failures.  I don't expect the glass to carry any tension, that will be the role of the geodesic members.  The glass would only be in bending, and hyperstatic bending at that, so probably not too severe if we keep the dimensions of the panes down to about 1m.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 04:57 AM
Sharp Cut


Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?


I take it I can continue designing a base around caves built by a machine such as the roadheader?

You asking permission?  :)

Mt. Sharp is our one case study:  the first martian sandstone formation to get a proper in situ geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf).  I'd think we could get a lot of mileage out of that, if we wanted to:  some exercise of tunnel-hab imagination.

What to look for?  Thick units, sure.  Sandstone or rock of similar hardness.  Good dips I suppose, for ease of excavation.  Low seepage.  High uniformity.  And?

And... Mars starts throwing curveballs, as always. 

In this case I'm thinking about toxins.  On Earth, sandstone is benign.  But sand doesn't accumulate perchlorates on Earth.  Where martian sandstone has aeolian origin, the original windblown dunes could have accumulated perchlorate salts.  Low-temperature compression and cementation would convert dunes to sandstone, but leaving perchlorates unaltered, within the final stone. 

Dig into that stone, pressurize chambers, turn on the heater -- and the humidifier.  What happens to the exposed perchlorates?

Or do you see better options in the Mt. Sharp stratigraphy?

(https://visitidaho.org/content/uploads/2015/10/st-anthony-sand-dunes-.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 04:59 AM
Exposed perchlorates, when heated in presence of moisture (and ubiquitous iron compounds on Mars) would probably release oxygen and become pretty benign. At least if you did things right. :)

But seriously. Perchlorates are both an energy and oxygen source.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 06:36 AM
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 07:01 AM
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat.
I'm not talking about astrobiology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 12:33 PM
Just being polite ;-)
Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

Anyone has a suggestion as to the maximum safe size (diameter) of a vault in a sandstone cave?


Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 01:30 PM
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.

So to be clear, the distinction is that the photons travel through a transparent substance to your eyes rather than via an array of CCDs then some circuits and ultimately OLEDs or whatever?  Seems a bit pedantic if it looks the same IMO.  I'm not talking about strapping on a VR headset and "exploring" Mars, I'm talking about replacing windows with like functionality.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 02:27 PM
There will always be artifacts if you look hard enough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:01 PM
There will always be artifacts if you look hard enough.

Obviously.  But for the sake of discussion, let's assume that it's a similar pixel density of a high-end phone or tablet display, and the sensor has some optical zoom ability, which you can control at the "window" if you want.

I think it would really be nitpicking at that point, in fact there are more obvious advantages to having the interactive digital window than I care to blab on about, IMO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/08/2016 03:24 PM
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:35 PM
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/08/2016 03:45 PM
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179

How does it work when several people are in the room?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:48 PM
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179

How does it work when several people are in the room?

I have no idea how it worked, and I don't remember what the vendor was.  However you can google autostereoscopic displays for more info.  Maybe it had a "subpixel filter?"
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/08/2016 05:03 PM
At some point 3d screens will work just like windows.
It requires huge processing power.
Each pixel needs to be a tv set unto itself.
Each pixel must directionally transmit light in a wide solid arc. Just like a glass windows does.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 08:56 PM
Sharp Cut

Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

re: perchlorate exposure:

Right, perchlorate accumulation would be a dry effect.  The perchlorates would be anhydrous in sandstone.

Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
 
So, looking at the geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf):

It confirms that Mt. Sharp has "an unconformity that separates hydrated from anhydrous rocks".  Above that unconformity are younger rocks that formed from dry windblown deposits.  That's where perchlorates could accumulate.  Below, older rocks; some of which appear to have formed in the presence of water, even within streams and lakes.  Subaqueous sand would have been rinsed clean of perchlorate salts prior to burial.  Net net:  if you're looking for non-toxic hab rock on Mt. Sharp, those strata below the unconformity would be the better prospects.

(subtext:  Amazonian sandstone is suspect hab material, universally, due to the possibility of perchlorate contamination.  At least to my mind.)

Can we glean any other prospecting clues from the geological analysis?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/08/2016 09:52 PM
(...)
Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
(...)

Could this be turned into a process for detoxification of newly excavated spaces?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 10:46 PM
(...)
Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
(...)

Could this be turned into a process for detoxification of newly excavated spaces?

Conceivably -- if, say, summoning the evil dead detoxes a graveyard.  :)

(http://cimg.tvgcdn.net/i/2015/10/23/a83e2ea2-e8df-41a2-bc38-78d1ab4e78e4/tumblrml4tklvlux1qgime3o1250.gif)

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/10/2016 04:43 AM
Sharp Cut

Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

re: perchlorate exposure:

Right, perchlorate accumulation would be a dry effect.  The perchlorates would be anhydrous in sandstone.

Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
 
So, looking at the geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf):

It confirms that Mt. Sharp has "an unconformity that separates hydrated from anhydrous rocks".  Above that unconformity are younger rocks that formed from dry windblown deposits.  That's where perchlorates could accumulate.  Below, older rocks; some of which appear to have formed in the presence of water, even within streams and lakes.  Subaqueous sand would have been rinsed clean of perchlorate salts prior to burial.  Net net:  if you're looking for non-toxic hab rock on Mt. Sharp, those strata below the unconformity would be the better prospects.

(subtext:  Amazonian sandstone is suspect hab material, universally, due to the possibility of perchlorate contamination.  At least to my mind.)

Can we glean any other prospecting clues from the geological analysis?

I think I see a few more clues to guide a hypothetical dig.  Briefly:

Most of the Mt. Sharp rock units are suspect hab material.  High thermal inertia units HTI1 and HTI2 might be dense, but they're young, hence probably of aeolian origin and potentially contaminated with perchlorate salts.   Layered sulfate unit LS contains, well, sulfate, possibly as magnesium sulfate (epsom salt), which would make for very soft, messy rock.  Phyllosilicate unit PhU is a crumbly mudstone. 

Only Murray Formation units MF1 and MF3 look useful.  These basal units appear to be of subaqueous origin, and would therefore be free of perchlorates.  They are also erosion resistant, suggesting some fracture resistance.  Their thermal inertia, and by inference density, is relatively high.  So all-in-all it looks as though MF1 and MF3 are the best units available for a hypothetical Mt. Sharp hab dig. 

Good enough?  Eh, maybe.  Feedback is welcome, etc.

So, hypothetically, where to cut?  Ideally you'd want to cut your entrance into some pre-existing exposure of MF1 or MF3.  You'd also want the tunnel to run up-slope for drainage.  And you'd want to tunnel without detours, with maximum rock uniformity and minimum uncertainty.

Guesstimating from the analysis paper, it looks as though one could attempt these minimal requirements by cutting into the Mt. Sharp contact, starting at the southwest wall of a half-kilometer crater on the edge of unit MF1.  Illustrating with shots from the paper, and Google Mars:

Image:  MtSharpHypothetical1.png

Units:  MF1 medium purple, MF2 light purple, MF3 dark purple.  Access crater at upper right. 

Image:  MtSharpHypothetical2.png

Crater detail.  Removal of loose crater debris would enable tunneling into wall at ~100 m depth. 

Image:  MtSharpHypothetical3.png

Straight-line distance from tunnel entrance to terminus at unit HTI1, 3.4 km.  Line in MF1/MF3 units.

Image:  MtSharpHypothetical4.png

Unit vs. Elevation (units near the hypothetical tunnel line profile; not an exact match).  Units:  MF3 dark purple, MF2 light purple with hematite deposits red, MF1 medium purple, HTI1 brown.  Red line is rise from tunnel entrance to terminus, at steady surface depth of 100 m.  Grade ~3%.



It might be interesting to see how current, "amazing," hab ideas could slot into this hypothetical tunneling site.  Assuming, again hypothetically, that some brine aquifer were discovered and accessed beneath the crater, and hab construction were judged both possible and desirable here, it might be interesting to collectively ballpark, say:

- A design of a dome over the crater
- Optimal layout of underground facilities, to accommodate maybe the first Spartan 300
- Time/energy requirements for the essential Roadheader work 
- Feasible size of some subterranean ("subaresian"?) garden dome

(serving suggestion only, below)  :)

(http://vignette3.wikia.nocookie.net/memoryalpha/images/a/ae/Ocampa_underground.jpg/revision/latest?cb=20061231200127&path-prefix=en)



Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 11/10/2016 03:03 PM
Why are we considering Mt Sharp / Gale Crater as habitat location?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/10/2016 03:06 PM
Why are we considering Mt Sharp / Gale Crater as habitat location?

I don't think we are. I have not heard of big water deposits at Gale Crater. Formations approached by Curiosity are just used as basis for discussing suitable types of formations for digging habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/10/2016 03:11 PM
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/10/2016 03:15 PM
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/10/2016 03:16 PM
We know the geology.
Just an exercise.

EDIT: in response to why mt. sharp
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/10/2016 03:18 PM
I personally like valles marineris.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/10/2016 04:09 PM
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/10/2016 10:01 PM
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 

Extraction of water from glacier or brine aquifer would be far more energy-efficient than extraction from regolith.  Rough calc:  A gypsum rotary dryer might need 75 kW of power to process 40 tons of regolith with 5% extractable water-mass, in one hour.  Excavation, transport, thaw, material processing and multi-step losses might add another MW.  Net:  ~4 billion J for 2 m3 of water.  Whereas a heater might melt that water from glacier with 700 million J.  Or reverse osmosis might extract the water from brine, using 20 million J. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/10/2016 10:38 PM
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

Interesting thought to bear in mind: a place with 10% water content in the regolith needs up to five times less energy to extract it than a place with 2%.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/11/2016 12:36 AM
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 12:49 AM
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 
...
No, because if you choose your location based on optimizing water gathering efficiency, it will place you nearer the poles. That compromises the energy production needed for electrolysis since we're reliant on solar power. Additionally, it increases the energy needed to get to orbit, thus requiring more energy still. So you can't optimize them separately, it must be coupled. If getting the water out is significantly less than electrolysis energy (since most of the water will be needed for propellant), then you should optimize for other things, like being close to the equator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/11/2016 03:59 AM
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 
...
No, because if you choose your location based on optimizing water gathering efficiency, it will place you nearer the poles. That compromises the energy production needed for electrolysis since we're reliant on solar power. Additionally, it increases the energy needed to get to orbit, thus requiring more energy still. So you can't optimize them separately, it must be coupled. If getting the water out is significantly less than electrolysis energy (since most of the water will be needed for propellant), then you should optimize for other things, like being close to the equator.

Facts first, math second, conclusion third.  Ideally.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 04:01 AM
I've done the math.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/11/2016 12:24 PM
I've done the math.

If you say so.  And let's remember that Step One, also.  But OT at this point, so somewhere else.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 11/11/2016 01:13 PM
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/11/2016 02:39 PM
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?

Most of these "Little House on the Martian Prairie" ideas will never be built because they don't fit into any sensible settlement architecture. However we get to hear about these ideas from mass media because they are good mass consumption content for media. Kind of like how some cable science channels are only showing pseudoscience shows nowadays. Very popular but also quite useless other than as light entertainment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 02:41 PM
Makin Mars and space in general a part of culture and the public's consciousness is critical to becoming a spacefaring civilization, especially because there's no terribly good economic reason to do so. Make space cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/11/2016 02:57 PM
Makin Mars and space in general a part of culture and the public's consciousness is critical to becoming a spacefaring civilization, especially because there's no terribly good economic reason to do so. Make space cool.

Exactly as Musk would have put it.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 05:28 PM
Sharp Thistle

OK, taking a shot at the Mt. Sharp hypothetical (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608175#msg1608175), expanding on Lake Matthew dome (http://www.lakematthew.com/wp-content/uploads/2016/06/hab_rough_geometry_v4_1920x901.png) methods:



Image:  MtSharpHypothetical2.png

Crater exposure of sandstone, entry point for tunnel into sandstone unit MF1.



Looking first at only the tunnel's crater entrance, how could that 500 m crater be put to use?

We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 



Image:  MtSharpHypothetical5.png

400 m subaqueous titanium/ETFE dome (white).



Water surfaces inside and outside the dome are marked in blue.  Note the surface just inside the dome perimeter:  this is the notional "moon pool" surface, which allows watergate access to the martian surface outside, sans airlock.

Prior to dome construction, debris sand would be removed via robotics and conveyor, piling outside the crater (purple).   Once the dome cushion modules are constructed and assembled together, the dome enters flotation through incremental addition of water to the moon pool trench, concurrent with increasing dome air pressure.  Water pressure counters air pressure in the trench.  Also concurrently, an open-air 30 m ballast track (green) is filled with sand to 20 m depth.  The fill is sand removed from the crater previously, now returned using the same robotics and conveyor as before.  Dome ribs go into tension, dome perimeter ring goes into compression.

At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.   Anchors require a mass of ~400 tons: ~170 tons grout, ~230 tons titanium.  The rest of the dome structure requires ~200 tons: ~60 tons ETFE, ~140 tons titanium.  Assuming all alloy is scavenge (from ITS plants, 3D printed into structural members), dome cargo totals ~230 tons.  If construction equipment also utilizes scavenged alloy (e.g., for the conveyor frame), it's likely the entire dome cargo mass, including construction equipment, would be less than the cargo capacity of a single ITS (450 tons).

After the dome enters operation, excavation of the crater floor can continue, and tunneling can begin (brown).  Removal of this debris requires airlocks.  Notionally, zipper truck sinter tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) (red) provide bulk airlocks for debris removal, with cars queued over 200 m within the airlocks.



Heating Problems

Cold sandstone (~-90 C on the coldest nights) presents big heating problems at this very hypothetical Mt. Sharp dome.

For example, anchoring could be a bit tricky.  The grout would have to set for at least a sol, at temperature above 5 C, to preclude any chance of ice formation and weakness.  Maybe that could be done using high-temp heater wire inside the titanium anchor's hollow core, to heat the grout from within.  Also, Mt. Sharp sulfates are a problem there:  Type V Portland cement would likely be required, with fly ash and volcanic ash, to protect the grout from sulfates mobilized in the wetted sandstone. 

Once the dome is in operation, heat conduction into sandstone presents an ongoing problem.  In rough terms:  At -90 C thermal conductivity of the sandstone increases to maybe 5 W/mK.  A 1 m layer of water on that -90 C sandstone would freeze in perhaps a week or so.  That 1 m freeze would present problems, for example, in watergate and moon pool operation.  Melting that 1 m layer would require ~9 trillion J.  If such immense heat energy were available, somewhere, it could be transferred through dome water to the ice.  However the crater's low boiling point (~5 C) would waste that heat:  water above 5 C would boil at the pool surface, quickly losing heat to the atmosphere, instead of the rock-bound ice.

It's a problem for this dome design, yes?



Incidentally, water losses from evaporation and sublimation should be manageable at that site, given hypothetical aquifer.  A 500 m pool, half covered in ice, would lose water at a rate of ~80 m3/hour; a rate readily countered by a hypothetical aquifer pump.

Also, very incidentally, the design looks a bit like a thistle, to my eyes.  So, Thistle Design, then.   :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/12/2016 05:50 PM
Where is the "Lake Matthew" thread? That'd be a better spot to discuss this.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 06:40 PM
Where is the "Lake Matthew" thread? That'd be a better spot to discuss this.

The Thistle Design is a hab, dealing with the same challenges any hab would encounter at this Mt. Sharp site.  There's no reason to move Thistle posts to another thread, just as there's no reason to move posts on towers, inflatables, glass geodesics, igloos, etc. to other threads.  Not if they're topical.  Or at least "amazing", I guess.

Actually it's interesting to compare the ways in which various designs address the challenges of a particular site.  Apples-to-apples, all that. 

What's your favorite?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/12/2016 07:19 PM
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?

Most of these "Little House on the Martian Prairie" ideas will never be built because they don't fit into any sensible settlement architecture. However we get to hear about these ideas from mass media because they are good mass consumption content for media. Kind of like how some cable science channels are only showing pseudoscience shows nowadays. Very popular but also quite useless other than as light entertainment.

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 07:48 PM
Sinter Block

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.

Some recent microwave regolith sintering refs and applications: Wilkinson et al. 2016 (https://www.researchgate.net/profile/Josef_Musil2/publication/303407153_Autonomous_Additive_Construction_on_Mars/links/5742082208ae298602ee2873.pdf).  Product looks a bit uneven still.  Better method?

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/12/2016 09:38 PM
Sinter Block

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.

Some recent microwave regolith sintering refs and applications: Wilkinson et al. 2016 (https://www.researchgate.net/profile/Josef_Musil2/publication/303407153_Autonomous_Additive_Construction_on_Mars/links/5742082208ae298602ee2873.pdf).  Product looks a bit uneven still.  Better method?

Looks like this is only a paper study, no actual experiments. Their idea is to use swarm intelligence with different robot types, smallest type does the sintering, which is not a good idea, where do they get the power from?

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression. Might work for cut and cover tunnels. The video shows a process that is quite hard to automate.

Still looking at references, "Additive Construction using Basalt Regolith Fines" Mueller, et al. from 2014 says TRL about 3, still a long way to go before ready for use on Mars.

Given what I've read I'm really surprised that this dome house uses microwave sintering of simulated regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 11:47 PM
Sinter Block

Looks like this is only a paper study, no actual experiments.

?  Paper refs for experiments:  Taylor and Meek (2005) and Barmatz et al. (2014).  Plus an experimental product is shown right there in the paper, photo Fig. 4e.  It's in the section on microwave sintering, titled

"Microwave sintering".

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression.

?  When you stack and bury the tunnel blocks, as in post and video, the tunnel is in compression, and can remain in compression even when pressurized to, for example, 60 kPa.  What are you trying to say? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 04:19 AM
Under the Dome

This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.

Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.



The Thistle Design has a max clearance of ~90 m at the dome crown.  So you could construct ~25-story buildings inside the dome, around the facility's central interior pond.  Or you could, in theory, build a 30-story central tower above the central pond, if foundation pillars were sunk into pond bedrock, or, alternately, if the surrounding buildings were designed to buttress and carry the central tower entirely above the pond.

And even the penthouse suites would be fully shielded from radiation.

It would be interesting to see how the structural and material requirements for such a Mars complex would compare, quantitatively, with the counterpart on Earth.  I'd imagine the complex could be considerably more open, for one thing.  Better views. 

Any architects want to tweak a reference tower under 0.38 g, to see just how the requirements change? 

And lamontagne, want to try your hand at a fanciful complex sketch, to spark creative thinking?

Image:  just for scale, though I'm not sure how to scale for hobbits.  :)

(http://farm4.static.flickr.com/3474/4562740618_6435213f0b.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/13/2016 04:46 AM
Under the Dome
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 07:17 AM
Sinter Block

Looks like this is only a paper study, no actual experiments.

?  Paper refs for experiments:  Taylor and Meek (2005) and Barmatz et al. (2014).  Plus an experimental product is shown right there in the paper, photo Fig. 4e.  It's in the section on microwave sintering, titled

"Microwave sintering".

That is not their experimental result, it is from Barmatz et al. (2014), and if you read that paper the experiments were on small samples in lab conditions. 200W microwave (don't say if it is input power or microwave power), 250 seconds to reach 400C (other places in the text mention 600C ), they also don't say the size of the sample, but given the average regolith grain size is small it looks to be about 1cm in diameter.

Given those figures it looks like 1MW can sinter 1 m3 in a day (24 MWh/m3).

Using 100kWh battery packs it would take 240 large robots to do the sintering autonomously.

EDIT: I'm surprised it takes so much power for sintering, perhaps I've made a mistake in the calculations or sintering small samples is not power efficient.

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression.

?  When you stack and bury the tunnel blocks, as in post and video, the tunnel is in compression, and can remain in compression even when pressurized to, for example, 60 kPa.  What are you trying to say?

Looks like only to about 10 kPa, they need about 10 m of regolith compression. Good for cut and cover tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/13/2016 12:39 PM
Lamontagne's towers can also work nicely if anchored in a cliffside and connected to tunnels at several levels. This makes the towers a vertical "outdoors" design element which ties together several levels of horizontal "indoors" elements.

Since the radiation protection is better inside the tunnels than in the towers, but the towers with their views and sunlight are better for providing a daily psychological booster, the use of towers built on cliffsides may be skewed more towards public/green spaces (such as farms, parks and Elon Musk's pizza joints) and generally attractions or places that people would want to visit, walk to or walk through several times a week.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 01:55 PM
Under the Dome
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.

The problem is that there's negligible shielding around the penthouse, as given, so the dosage would be even higher than in e.g. McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1), where 15 cm omnidirectional aluminum shielding was assumed.  Women under 40 would be especially vulnerable in the penthouse, approaching career exposure limit in the first synod.  On lower floors the tower would expose two-synod crews to dosages approaching limit. 

That's not good for multi-synod missions, much less settlement ambitions.  Hence the need for explicit and significant shielding in this or any long-duration hab.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 02:03 PM
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.

I really like these. Central core can carry elevators and utilities. Construction techniques similar to tower blocks on Earth.

From outside would look not too disimilar to https://en.wikipedia.org/wiki/St_George_Wharf_Tower or https://en.wikipedia.org/wiki/30_St_Mary_Axe
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 02:20 PM
For radiation reduction fit the towers with a sombrero. A couple of meter thickness of low atomic mass structure (swimming pool?). Very few cosmic rays come from the sides as the atmospheric depth is much greater towards the horizon.

Would still get a great view.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 04:03 PM
... they need about 10 m of regolith compression. Good for cut and cover tunnels.

Cover to suit, but the scenario does place a notional Roadheader (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1607257#msg1607257) on soft sandstone.  So why not use the Roadheader to cut, you know, the road?

...if you read that paper the experiments were on small samples in lab conditions.

If you read the paper you do see that, yes.  And 200 W is microwave power:  lab experiments aren't concerned with wall-plug efficiency. 

There is the option of sulfur concrete (https://arxiv.org/pdf/1512.05461.pdf).  Given that rich sulfate deposits are located within 6 km of the site, one could consider fabrication of the tunnel blocks from sulfur concrete, instead of sinter.  Net energy requirements might determine the method.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/13/2016 07:38 PM
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.

The problem is that there's negligible shielding around the penthouse, as given, so the dosage would be even higher than in e.g. McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1), where 15 cm omnidirectional aluminum shielding was assumed.  Women under 40 would be especially vulnerable in the penthouse, approaching career exposure limit in the first synod.  On lower floors the tower would expose two-synod crews to dosages approaching limit. 

That's not good for multi-synod missions, much less settlement ambitions.  Hence the need for explicit and significant shielding in this or any long-duration hab.
Well sure. I would personally avoid a penthouse. Put something else like a water tank or vertical farming in the top levels.

Given we don't know the exact risks of radiation, underground is the safer option. And there are lots of other reasons too. I would definitely not charge off to mars having bound myself to the assumptions of towers. That is not going to happen though.

I was just comparing towers to other things we may put on the surface for whatever reason. A pent house on top would be no worse than a dome on the ground, and for lower levels it gets successively better.

Supposing radiation proves to be a huge problem, but it turns out that people psychologically need to look out real windows at a real horizon, towers are an excellent option for an above ground portion of your colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/13/2016 08:04 PM
My idea for a dome habitat would be an appartement tower in the center. Thick roof on top for radiation protection. Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

Around the tower would be a garden. Nice to have an outside of the living space with plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 10:23 PM
Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

If you were building dome and towers concurrently, you might integrate the loads.  It could reduce the number of anchors, somewhat.  However in most scenarios I think the dome goes up first, and any towers go up after, just due to the brutal site logistics.  Separated loads simplify construction.

Around the tower would be a garden. Nice to have an outside of the living space with plants.

Yes, it would be nice.  It's one reason the Thistle Design carries over the "hanging garden" of the notional Lake Matthew greenhouse.  A building complex with central tower could be raised to 30 stories.  Outside this complex are ~20 stories of dome-suspended garden:  for ballast against air pressure, for self-sufficiency, and of course, for the view.

When it's all done, connect building stories to garden stories.  With rope bridges?

(https://media-cdn.tripadvisor.com/media/photo-s/06/33/c9/bc/the-lost-gardens-of-heligan.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/14/2016 08:20 AM
Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

If you were building dome and towers concurrently, you might integrate the loads.  It could reduce the number of anchors, somewhat.  However in most scenarios I think the dome goes up first, and any towers go up after, just due to the brutal site logistics.  Separated loads simplify construction.

Yes, I am assuming they would be built concurrently, if that were the design. In the sense that it is one project. Much easier to build the building first, then build the dome around it.
I don't think separated loads simplify construction. They simplify design but what is design complexity on that level in the age of computer simulation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: CapitalistOppressor on 11/14/2016 04:05 PM
Here is an elaborate concept for a city built under airless conditions, circa 1987

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/15/2016 06:09 AM
Here is an elaborate concept for a city built under airless conditions, circa 1987

Neat. ECLS and interfaces to other spheres at the bottom, oxygen and water tanks on top, habitable floors inbetween.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/15/2016 08:10 AM
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1387863;image)

I think they copied that directly from here: St. Peter's Basilica

(https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Petersdom_von_Engelsburg_gesehen.jpg/1280px-Petersdom_von_Engelsburg_gesehen.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: CapitalistOppressor on 11/15/2016 03:26 PM
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1387863;image)

I think they copied that directly from here: St. Peter's Basilica

(https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Petersdom_von_Engelsburg_gesehen.jpg/1280px-Petersdom_von_Engelsburg_gesehen.jpg)

While Spaceball City was intended to be funny, it points to the fact that using spherical pressure vessels as habs, and having that concept inspire visions of off world cities is hardly new. 

IIRC Spaceship Earth at Epcot center was designed by Ray Bradbury, and shows that any serious thinking on the subject tends to quickly converge as the engineering realities dominate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 04:41 PM
Tunnel Trouble

An apparent problem for the Mt. Sharp Cut:  sandstone porosity

Was noodling on the notion of room-and-pillar (http://www.slideshare.net/hzharraz/room-and-pillar-mining-method) tunneling for extended hab space, beyond the notional Thistle Design's dome space.  The MF1 sandstone unit would be soft enough to cut with Roadheader.  However, porosity raises a problem for room-and-pillar tunnels.  Just ballparking, but what I see is:

MF1 thermal inertia (TI) is ~360 J/Km^2s^0.5.  This is "well-cemented sedimentary rock (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf)". 

But gypcrete ain't granite, and the cementing will be insufficient if the sandstone porosity is too high for compressive load.

A sandstone TI of 360 would have max, best-case density (http://onlinelibrary.wiley.com/doi/10.1029/2007JE002910/full) of ~2000 kg/m3.

That max density equates with porosity (http://petrowiki.org/File%3AVol1_Page_582_Image_0001.png) of 0.4.

Porosity of 0.4 equates with uniaxial compressive strength (UCS (http://)) of, effectively, zilch.

(http://petrowiki.org/images/7/77/Vol1_Page_652_Image_0001.png)

Result:  That means no pillars, however wide, can handle the load in a Mt. Sharp room-and-pillar scheme.  The rooms would not be safe without extensive shoring / anchoring of the ceiling, which would be a massive effort, literally and figuratively.



To attempt the room-and-pillar method, a sandstone of porosity < 0.2 would be required.  This equates with density > 2300 kg/m3, and TI > 500 J/Km^2s^0.5.

Somewhere else, apparently.

If I read that right.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2016 05:18 PM
How very annoying of sandstone's part!

Perhaps the non weathered sandstone a few yards deeper is less porous though, since a pososity of 0.4 means we have 40% of void in the rock?  So its a lot more sand than stone!

Somewhere else then, or tougher rock, slightly metamorphic sandstone?  After all sandstone was used to build this:

The Strasbourg cathedral, build from pink sandstone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 06:47 PM
Miner's Prospects

How very annoying of sandstone's part!...  Somewhere else then, or tougher rock, slightly metamorphic sandstone?"

Yeah, annoying and rather uncooperative.   :(

Metamorphism is very slight on Mars, absent tectonics.  So your parent material would need lithifying burial even deeper than that encountered by the Murray Formation units.  They're, what, maybe 1.3 km below the unconformity?  So exposures cutting deeper than that, I guess.

And the rock would probably need to be pre-Amazonian, because of aeolian contaminants.

The strength indicator would be an observed thermal inertia somewhere between 500 and 1000 J/Km^2s^0.5, I guess.  Having compressive strength, but not too much!   :o

Not an easy hunt.  But maybe a useful one.   What do you think, you want to go prospecting on NSF grant?

(http://3.bp.blogspot.com/_MtI4h_P-1ts/Sv8L22iuZsI/AAAAAAAAAF4/_wlG_IF23w8/s400/TheOldProspector.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2016 07:00 PM
Miner's Prospects

How very annoying of sandstone's part!...  Somewhere else then, or tougher rock, slightly metamorphic sandstone?"

Yeah, annoying and rather uncooperative.   :(

Metamorphism is very slight on Mars, absent tectonics.  So your parent material would need lithifying burial even deeper than that encountered by the Murray Formation units.  They're, what, maybe 1.3 km below the unconformity?  So exposures cutting deeper than that, I guess.

And the rock would probably need to be pre-Amazonian, because of aeolian contaminants.

The strength indicator would be an observed thermal inertia somewhere between 500 and 1000 J/Km^2s^0.5, I guess.  Having compressive strength, but not too much!   :o

Not an easy hunt.  But maybe a useful one.   What do you think, you want to go prospecting on NSF grant?


Crashing meteorites will have produced some amount of metamorphism, and along the edges of volcanic plateaux there will be materials that have been modified by heat, and then buried, and then eroded away.  We don't need a gigantic area, after all, to build a city.  Just a set of conditions.
we're a bit far to go out with our hammer and microscope ;-).  I think at this point we should just decide if it is probable that such a combination can exist : Chemically clean, relatively soft rock, close to a good source of water, ideally with horizontal access.  Do all the mechanisms to create this exist on Mars?  If so, we can go ahead and fiddle with a city plan.  Schools, atriums, public areas?  Storage and functionalities? What type of city would be built, if started from scratch today? 


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 07:49 PM
Chemically clean, relatively soft rock, close to a good source of water, ideally with horizontal access.  Do all the mechanisms to create this exist on Mars?

The mechanisms exist, or existed.  Have time and place conspired?  Dunno.

...we're a bit far to go out with our hammer and microscope ;-).

Still, you could go a long way with the existing maps of geology, topography and thermal inertia.

Chris should totally spring for the NSF grant, my opinion.   ;D



Update:  a nice contextual side-by-side (https://marstherm.boulder.swri.edu/) of apparent thermal inertia at our hypothetical Mt. Sharp worksite, and across the planet. 

With MARSTHERM "prospecting software".    8)

(https://marstherm.boulder.swri.edu/images/GaleCraterTesSeason.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/18/2016 08:27 PM
I've been in sandstone tunnels. I can tell you the strength isn't "zilch."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/18/2016 08:35 PM
How very annoying of sandstone's part!

Perhaps the non weathered sandstone a few yards deeper is less porous though, since a pososity of 0.4 means we have 40% of void in the rock?  So its a lot more sand than stone!

Somewhere else then, or tougher rock, slightly metamorphic sandstone?  After all sandstone was used to build this:

The Strasbourg cathedral, build from pink sandstone.

Yep. The medieval city walls of Famagusta, Cyprus, a big cathedral and Othello's Castle are all built from locally carved sandstone blocks, and they are still standing. Plus there are centuries old tunnels inside Famagusta's walls everywhere.

And let's not forget that the chemical bond strengths of two identical blocks of sandstone on Earth and Mars are the same, but Mars gravity is more forgiving at 0.38g.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 08:55 PM
I've been in sandstone tunnels. I can tell you the strength isn't "zilch."

Have you built sandcastles, too?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/18/2016 09:31 PM
I've climbed a lot of sandstone, it varies from cheese to almost as hard as rock. I guess the answer is 'it depends'.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rei on 11/19/2016 02:30 AM
I'm not sure how to interpret the sedimentary rocks in pictures from the rovers in terms of strength.  They often seem to have "pancakes" of sediments jutting out to a degree I've never encountered on Earth.  I guess that means that the resistant layers must have some pretty good tensile strength (although the low gravity and lack of precipitation or strong winds surely also contributes to them not breaking off).

My personal experience is mainly with igneous rock (common on Mars).  Which is generally terrible, if your goal is low porosity or structural integrity in general (in addition to being loaded with vesicles, it tends to be highly fractured, as it cracks during cooling).  On the other hand, tuff is more of a sedimentary rock. I'm not sure of how good its gas permeability is, but it's easy to work, and can nonetheless be quite durable.  Some can also be a source of pozzolan for making pozzolanic concrete, which has lower porosity and greater durability than a simple portland cement concrete.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/19/2016 05:07 AM
Yuty Prospect

Maybe Yuty Crater (http://www.lpi.usra.edu/publications/slidesets/craters/slide_6.html)?
2212'N, 34W

Pros:
- Late Hesperian (https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/thumbnails/image/6-Mars-a1.jpg) bedrock, likely ice-rich at time of impact (relatively clean rock, not aeolian)
- Unusually large central peak (possibly retaining pingo or other useful ground ice concentration)
- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
- Wall exposure to ~1.5 km depth
- @22 N, good relative PV and temperature.  NW wall catches the sunlight.

Cons:
- Apparent thermal inertia suggests rock is near the low end of viable UCS.  However the notional TI/UCS rule-of-thumb is only ballpark, especially when rock type is speculative.
- Impact fracturing for weakened / shattered wall rock?
- ( ? )



Image:  YutyHypothetical1.png

Yuty Crater, showing bedrock exposures, NW exposure to left.  From video:  Mars Express, 2x vertical exaggeration (Yuty @1:00)

https://vimeo.com/125630557

Image:  YutyHypothetical2.png

Yuty Crater Thermal Inertia, red > 500 J/Km^2s^0.5

Image:  YutyHypothetical3.png

Yuty Crater night-time temperature with relatively warm wall exposure (red), suggesting highest UCS.  Showing also lobate ejecta, suggesting bedrock that was ice-or-water-rich at impact.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/22/2016 08:05 AM
What about a dome within a dome within a dome ?
Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/22/2016 08:57 AM
What about a dome within a dome within a dome ?
Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.

Sounds fine as long as everything is within specs. But a breach in one of the three domes and everything comes down like a house of cards, or maybe better like dominoes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/22/2016 09:17 AM
We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 
400 m subaqueous titanium/ETFE dome (white).
[...]
At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.

If you mean that the water around the dome is 5m deep, then your net upward force is around 1.4 billion N; air pressure plus buoyancy. If you mean that the water covers the dome by 5m, the net upward force from buoyancy alone is 6 billion N.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/22/2016 09:36 AM
What about a dome within a dome within a dome ? Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.

You aren't really saving anything. Force scales linearly with pressure, so the net force is the same.

And either you've got a single set of deep anchors holding all three domes or three times as many shallow anchors. But the net force on those anchors, and thus the sum-total depth of anchorage, must be the same.

[Of course, if you have three independent rings of anchors, the second domes must be larger than the inner dome by enough space for its anchors to be biting into virgin rock, the outermost dome larger again. And larger domes experience more force that smaller ones, proportional to the square of radius. But force from atmospheric pressure only reduces linearly. So the net effect of your dome-within-a-dome-within-a-dome is that you end up needed to contain more force with three domes than one.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/22/2016 12:49 PM
Buoyancy and Ballast

We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 
400 m subaqueous titanium/ETFE dome (white).
[...]
At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.

If you mean that the water around the dome is 5m deep, then your net upward force is around 1.4 billion N; air pressure plus buoyancy. If you mean that the water covers the dome by 5m, the net upward force from buoyancy alone is 6 billion N.

Net 800 million N in this notional, ballasted configuration, yes.  Be sure to include the ballast.

Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rei on 11/22/2016 01:11 PM
- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
...
- Impact fracturing for weakened / shattered wall rock?

Basalt is almost always highly fractured, impact or not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/22/2016 03:27 PM
The Least Unkindest Cut

- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
...
- Impact fracturing for weakened / shattered wall rock?

Basalt is almost always highly fractured, impact or not.

The important thing is UCS.  If impact fracturing shatters the rock, UCS tanks.  And complex craters like Yuty Crater have a lot of impact fracturing:

(http://www.newgeology.us/WWBowlComplex.jpg)



Image:  YutyHypothetical1.png

As evidence of shatter at Yuty Crater, we see extensive slumping in the NW wall (left).  Apparently some of the wall shattered on impact, lost its UCS, and collapsed. 

If there's more shattered rock in that wall, extending hundreds of meters in, the effort to shore up a tunnel entrance through that mess could be prohibitive.

Also the Yuty Crater rock wouldn't be parent basalt, but cemented sediment with basaltic grains, as opposed to, say, glassy grains.  Basaltic grains would explain the wall's relatively high TI (~600) which is nonetheless lower than that of parent basalt.  Even a basalt with a high porosity (0.4) would have a higher TI (~1000).



How to get around the UCS uncertainties stemming from impact violence to bedrock?   

Maybe one could prospect for exposures that were cut more gently, such as cuts from catastrophic floods, or from glacial scour.  These cuts would not produce shattered rock. 

Maybe, for example, somewhere along the 2.5 km cliffs of Kasei Valles?

(http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2006/08/kasei_valles_perspective_view_of_northern_branch_looking_west/9265323-5-eng-GB/Kasei_Valles_perspective_view_of_Northern_branch_looking_West_node_full_image_2.jpg)

Prospecting is hard work.   :-\
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 02:06 AM
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/23/2016 03:02 AM
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.
Im finding it a bit hard to get my head around this. I know that the weight of water sometimes makes it hard to pull out the plug at the bottom of a sink. I also know that something underwater containing air pushes up.

In the second case I can see why. The pressure of the water beneath is greater than the pressure of the water on top, because it is deeper.

As far as I can tell if something is sealed to the bottom it only feels the downward pressure and the situation is more like the plug at the bottom of the sink. But if it springs a leak then it becomes a huge flotation device and the roof instead of resisting compression must now resist stretching like a pressure vessel.

I get even more confused trying to picture the case in between compression and tension.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 03:24 AM
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.

Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:

https://www.youtube.com/watch?v=t-0iJ25zbcs
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 03:51 AM
Other Prospects

Bandfield et al. 2013 (http://faculty.washington.edu/joshband/publications/bandfield_global_crust.pdf)

Quote
On Mars, competent bedrock and block-dominated surfaces are
rare in older terrains. Less than 1% of the martian surface is composed
of surfaces dominated by high strength rocks, and exposures
of materials such as high strength blocky lava flows are extremely
rare (Edwards et al., 2009; Fig. 11). In addition, extensive regions
completely lack exposures of high strength rocks. Where we have
the ability to probe the martian subsurface through craters, canyons,
and other topographic features, THEMIS, CTX and HiRISE
observations suggest that the older martian crust is typically
mechanically weak and composed of weakly consolidated fine particulates.
By contrast, younger terrains of Hesperian and Amazonian
ages commonly show evidence for high strength crustal
materials where subsequent dust mantling and periglacial processes
have not occurred.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 06:59 AM
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:
https://www.youtube.com/watch?v=t-0iJ25zbcs

Conclusion of the video: "The buoyancy force is equal to the the weight of the displaced liquid"

What exactly did you think you were trying to prove?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 09:07 AM
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Im finding it a bit hard to get my head around this. I know that the weight of water sometimes makes it hard to pull out the plug at the bottom of a sink. I also know that something underwater containing air pushes up. [...]
As far as I can tell if something is sealed to the bottom it only feels the downward pressure and the situation is more like the plug at the bottom of the sink. But if it springs a leak then it becomes a huge flotation device and the roof instead of resisting compression must now resist stretching like a pressure vessel.

When the plug is over a pipe full of air, the plug experiences more weight than buoyancy. But... and this is the key bit... the pipe-plus-plug combination is still experiencing buoyancy. The pipe is just bolted down sufficiently so you don't notice it.

But you can simulate this by filling a sink/bath/pool/etc with water and playing with a couple of bowls and a plate. (Neutrally buoyant is preferable, but slightly heavier than water is fine.)

Get a bowl and invert it, submerge it while capturing a nice big air-bubble, then let it go and it'll immediately rise up. Exactly as you expect. But even when you push it against the bottom of the sink/bath/pool/etc, the buoyancy is still present. It doesn't actually require water under the bowl.

"Ah", you think, "the water leaks under the rim, breaking the... seal... or... something." But the surface tension of water is enough to prevent this at ordinary pressures. You can show this by "cupping" two bowls, one upright and one inverted on top. Submerge them and the bottom (upright) bowl won't fill with water until you let the top bowl lift away. (If you raise the top bowl, rather than just letting it go, you can keep the air-bubble trapped under it, releasing only the air in the bottom bowl. Letting you see more clearly that the bottom bowl was indeed dry until that moment.)

This works even if the contact between the rims of the bowls is pretty uneven. If works when the gap is visible.

Note: If you hold the bottom bowl and let go of the top (inverted) bowl, the top bowl will immediately rise, just as it does normally. There's no suction from the air in the bottom bowl.

Now submerge the inverted bowl again, but this time put a plate under the bowl, essentially using a plate instead of the bottom of the sink/bath/pool/etc, when you let go of the bowl, it still rises immediately. Same as it did when you pressed it against the bottom of the sink/bath/pool/etc.

Now repeat this with the bowl upright (opening at the top) and the plate on top. Submerge the two together. Not only will water not leak under the plate (as mentioned, surface tension of the water is enough to prevent leaks at this pressure), but as long as you hold onto the bowl the plate will happily sit on top of the air-bubble, the plate won't lift up when you let it go. (The plate easily slides from side to side, there's no real "seal".) That's the same effect that keeps your plug plugged. You can even "burp" the plate a few times and it will tend to get sucked back down onto the bowl (just as the sink plug does.)

Now let go of the bowl too.

The bowl/plate combo remains as buoyant as it was when inverted. (And obviously, you'll realise this while having to hold the bowl down.) This is the same buoyancy that also acts on the drain-pipe of your sink, just without you realising it.

It's the thing actually displacing the liquid which experiences the buoyancy, not the plug on top.

And in wstewart's proposals, that's the dome. It will experience an upward force equivalent to the weight of 6 million tonnes of displaced water trying to tear it off its anchors. The water just makes the dome problem worse.

---

Aside: Video of a buoyant "plug" because I'm easily amused.

https://www.youtube.com/watch?v=P5uxv2ZJPTc
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 05:33 PM
F(bot)

Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:
https://www.youtube.com/watch?v=t-0iJ25zbcs

Conclusion of the video: "The buoyancy force is equal to the the weight of the displaced liquid"

What exactly did you think you were trying to prove?

As in Prof. van Biezen's video, displacement puts the object's lower surface in contact with the liquid.  And as in the video, liquid pressure contact exerts upward force F(bot) on that surface.

F(bot), and only F(bot), is the upward buoyancy force.

Thistle Dome lacks that lower surface contact, so there's no liquid displacement, no F(bot), no upward buoyancy force.  The only upward force is air pressure * area.  Accounted for.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/24/2016 01:54 AM
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,

A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.

Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/24/2016 03:31 AM
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,

A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.

Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.

No, you just confused force from air pressure with buoyancy force. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/24/2016 07:48 AM
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.

Buoyancy is in addition to the uplift from air-pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/24/2016 03:29 PM
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.

Buoyancy is in addition to the uplift from air-pressure.

It doesn't work that way.

(http://i.imgur.com/pJ6MSei.gif)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/25/2016 06:16 AM
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.
Buoyancy is in addition to the uplift from air-pressure.
It doesn't work that way.

So try it.

An air-filled dome fully-submerged on the bottom of a tub of water should (according to your reasoning) experience no buoyancy, provided there's no water underneath the dome. And without the 600kpa excess air-pressure, it should experience no lift at all. In fact the dome should be held down by the weight of the column of water above it.

Go try it.

(https://s-media-cache-ak0.pinimg.com/originals/2f/5d/d2/2f5dd2541f167b50584360dbecf63a2c.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/25/2016 07:56 AM
How about this? what I have done is place a glass bowl in a sink over the plug, right way up, and taped some plastic sandwich wrap over it, sealing the edges firmly. Then I filled the sink with water.

I argue that all the plastic-wrap that is clearly curved downwards is feeling a downwards force. No part of it attempts to form an upwards bubble.

(http://i68.tinypic.com/2s6rq0n.jpg)

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell. I think it formed a proper seal and thus no air could be pushed out and down the plughole. Im sure that if I had used a bowl with a way for air to escape down the plughole, it would have formed a downwards curving dome.

Note: when I pulled a corner of the black tape up allowing water to enter, the plastic wrap immediately converted to an upward pulling dome shape, even as the water began pouring down the plughole.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/25/2016 11:29 AM
How about this?

Nice! At least someone is willing to play along. Props for getting a good seal with the tape.

I argue that all the plastic-wrap that is clearly curved downwards is feeling a downwards force.

Mainly an inward force from the sides, I suspect.

I did something similar, but using a plate as a base and a tall narrow glass as a central support. The sides bowed inwards, exactly as yours, but the air gathered around the top and pushed upwards. Essentially it tried to form a buoyant sphere.

[My tape wouldn't stick to the sink surface enough to stop the glass'n'bubble from lifting off (too damp, I expect, even after I dried it). So I had to resort to sticking it to the plate, which had to be held underwater by hand, so no pics. Sorry. I might try with the bathtub tomorrow. It needs cleaning anyway.]

Hence...

No part of it attempts to form an upwards bubble.

...I suspect in your set-up, some air was able to leak through out the drain.

Try repeating it with a plug in place, or on a solid part of the sink.

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell.

You get the same effect when you place a flat plate over a bowl. The bowl remains buoyant, but the plate sits loosely on top of the bowl. Neither lifted by the air, nor pressed down by unsupported the column of water. Its buoyancy is exactly the same as if the air-filled bowl wasn't there.

Did you try getting an air-filled bowl (inverted) to sit on the bottom of the sink, like wstewart's dome?

Interestingly, you can get a solid-but-buoyant object to "stick". With difficulty. If the bottom of the object and the tub are both very flat and you add a hydrophobic layer between them (lard!). In order to lift, it must create a vacuum. A small change in height creates a large increase in "volume" below the object, hence a large reduction in pressure, enough to resist buoyancy.

But no matter how much grease I slather around the base of a "dome", it will not stay down. A small lift creates almost no change in air pressure inside the dome, hence no resistance to buoyancy. The same will be true of wstewart's dome (or worse because of the over-pressure.)

I suspect the only way to "stick" a dome would be to pump the air out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/25/2016 04:11 PM
Moon Pool

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell.

Because...?

There's no tension if no net force.  Here weight of water above the film is a force of same magnitude as force from air pressure below. 

Note: when I pulled a corner of the black tape up allowing water to enter, the plastic wrap immediately converted to an upward pulling dome shape, even as the water began pouring down the plughole.

Because...?

Drainage reduces water depth above the film, and weight.  Result:  net upward force, putting film into tension as a dome.

(And of course, no F(bot), no buoyancy force.)



Seal the drain and water enters the dome until base water pressure equalizes with dome air pressure. 

Result:  moon pool (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957)

Would be funny to see model astronauts exiting your dome through a moon pool.  Elon would totally twig on that.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/25/2016 10:14 PM
No part of it attempts to form an upwards bubble.

...I suspect in your set-up, some air was able to leak through out the drain.

Try repeating it with a plug in place, or on a solid part of the sink.
That was by design though. There was always a bit of water trickling in but it was slow enough that it didn't equalise the pressure. When I pulled up the edge, it immediately ballooned upward into a dome.

Ah. I just realised something. I haven't really been following the exact subject that the moot is about. Something about buoyancy vs being weighed down.

I don't dispute that the buoyancy would lift up a sufficient portion of whatever ground the dome is attached to. If the ground is not one monolithic solid object then water pressure can get beneath and start pushing.

I think the actual interesting question is this: Is the force of buoyancy transmitted through tension on the plastic film pulling, or from pushing from beneath, ie does the dome material have to be built to withstand those huge lifting forces?

In my experiment the film over the top of the bowl was flat, not under tension. I believe any lifting pressure was on the underside. IMO your base has to be strong, watertight, and of sufficient mass, but your roof material can be weak.

Im not sure if this is exactly what you guys were discussing though. The above can be tested more simply by just taping a plastic cover under over a bowl and holding the bowl underwater by force. My guess is that the plastic film roof would remain fairly flat and not strain upward, probably dip down sightly due to pressure, though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof. Ideally the strong part is a monolithic lump of rock that is large enough that dome+rock mass/volume exceeds density of water.

(I just tested this and of course it is true. The top of the bowl does not bulge upwards. It had a slight downwards curve but was hard to judge. I expect if the water was deep enough it would bulge downward because the air inside is being compressed by the water sitting on top of it.)



Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 03:57 AM
though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.

Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy.[*] To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.

The buoyancy is present no matter what you do.

Wstewart believes that he can treat it as a ballast force and ignore the buoyancy, that submerging a dome actually makes things easier.

[*Other than from it's own internally generated displacement volume, which is trivial.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/26/2016 04:47 AM
though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.
Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy.[*] To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.

The buoyancy is present no matter what you do.
Im not fussed about that part though. The dome has to be connected to a massive monolithic piece of stone. The stone has to perform the roll of this bowl. If the density of the dome+stone is less than that of water, it would rise.

The only interesting point to me is that the material of the dome itself does not feel huge forces, or any particular force at all if the air pressure inside balances the water pressure outside. Even at the edges where it connects to the stone it does not feel any pressure like you would experience trying to hold down a diving bell.

There is huge pressure trying to pull this thing up but it is not transmitted by the roof material tugging upwards. Rather the roof has lessened the weight of the column of water pressing down from above, and it is this imbalance that tries to lift the floor up if any ambient water pressure can get beneath it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 05:48 AM
Erebus Montes Prospect
34 N 177 W

Maybe an improvement on the previous prospects for accessible tunnel-ready rock with nearby ice deposits.

Pros:

- Early Hesperian rock, probably without aeolian contaminants
- > 600 TI, exceeding minimum UCS for tunneling
- 1 km sunlit exposure at 34 N, for good PV
- widespread evidence of geologically recent glacial and periglacial effects, for possible remnant subsurface ice

Cons:

- -3800 m entrance elevation, marginal atmospheric pressure for liquid water
- rock type(s) and UCS uncertain
- remnant subsurface ice concentration unknown
- no crater at tunnel entrance locations; wall/plain structure required



Image:  ErebusMontesHypothetical1.png

High TI units outlined, esp. in Arcadia Planitia, from Bandfield et al. 2013 (http://faculty.washington.edu/joshband/publications/bandfield_global_crust.pdf).

Image:  ErebusMontesHypothetical2.png

Glacier-like forms, esp. in Arcadia Planitia, from Souness et al. 2012 (http://geomorphology.sese.asu.edu/Papers/souness_etal_2012.pdf).

Image:  ErebusMontesHypothetical3.png

Block mesas near Erebus Montes, possibly with remnant glacial fill between blocks.  1 km sunlit southern exposures.  Note filled crater 2 km S of mesas, possibly with remnant subsurface ice.

Image:  ErebusMontesHypothetical4.png

Night IR of mesas, showing higher TI of exposures (brighter).

Image:  ErebusMontesHypothetical5.png

Debris apron around mesa, possibly with remnant glacial fill.

Image:  ErebusMontesHypothetical6.png

Concentric crater fill example, 50 km SW of mesas, possibly with remnant subsurface ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 07:28 AM
Im not fussed about that part though. The dome has to be connected to a massive monolithic piece of stone. The stone has to perform the roll of this bowl. If the density of the dome+stone is less than that of water, it would rise.

That was what started this. Wstewart believes that submerging the dome reduces the upward force from the air-pressure. That the water acts as ballast and doesn't add an entire extra buoyancy effect to deal with.

though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.
Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy. To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.
The only interesting point to me is that the material of the dome itself does not feel huge forces, or any particular force at all if the air pressure inside balances the water pressure outside.

That's not the case. You are confusing the flat cover (which doesn't experience buoyancy) with the walls of a dome.

The dome will be crushed in from the side, and push up through the top. (Essentially it's trying to form a sphere at the same time as it's trying to rise.)

and it is this imbalance that tries to lift the floor up if any ambient water pressure can get beneath it.

It doesn't require water underneath, it only requires the absence of a vacuum wide enough to overcome the net buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/26/2016 08:01 AM
That's not the case. You are confusing the flat cover (which doesn't experience buoyancy) with the walls of a dome.

The dome will be crushed in from the side, and push up through the top. (Essentially it's trying to form a sphere at the same time as it's trying to rise.)
That might be true. I did actually wonder about that before reading this, and if I should repeat the experiment with something other than a flat surface.

It is still not a big issue to me. For something underwater I don't care about the sides. The roof could be a flat surface and not a dome if it turns out that is the only shape to which this principle applies. Simply by making the area sufficiently large, the cost of the walls becomes a small fraction of the cost of the roof, which does not need any particular strength if the air is at the same pressure as the water. At 30 meters on Mars that would match earth sealevel. I imagine pillars dotted around because even if the roof is at equilibrium, it is not particularly stable and could even exhibit waves.

The transparent roof could be quite cheap. The underside can be as cheap, rigid and as heavy as you like, ideally a massive piece of ground but it could also be a freefloating thing build of concrete or whatever.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 01:02 PM
Cheap Digs

The roof could be a flat surface and not a dome...

Yes.  Thistle Dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957) has slight curvature for tensioning and aesthetics.

...the roof, which does not need any particular strength if the air is at the same pressure as the water. At 30 meters on Mars that would match earth sealevel.

Yes.  Thistle Dome moon pool (stemwall base) is at ~15 m because dome is at 60 kPa.  Crown exterior is notionally at 3 m (sunlight through shallow water).  Surface in tension, perimeter ring in compression.

I imagine pillars dotted around because even if the roof is at equilibrium, it is not particularly stable and could even exhibit waves.

A single-piece film would be a wavy mess all right, and hard to fabricate at scale.  In contrast, Thistle Dome is conceptually modular:  hexagons fabricated in shirtsleeves, lifted through the fab roof airlock one-by-one for dome assembly.   Titanium ribs for rigidity.  No waves.

The transparent roof could be quite cheap. The underside can be as cheap, rigid and as heavy as you like, ideally a massive piece of ground but it could also be a freefloating thing build of concrete or whatever.

Bedrock is cheap, yep.  ETFE is not as cheap (http://www.polymerplastics.com/fluoro_tefzel.shtml), but you'd expect bulk discount.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 01:31 PM
For something underwater I don't care about the sides.

Work out the crushing force per square metre.

And you've still got to deal with the buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 03:37 PM
Cooler Insulation

If room-and-pillar tunneling should prove feasible, how might the space be thermally regulated?

Near-surface rock averages ~ -60 C at useful latitudes, and living quarters would be in direct conductive contact with that rock.  Insulation would be necessary, and lots of it.

For comparison, the South Pole station is elevated off the ice, minimizing conductive heat loss.  Even so, insulating panels are pretty thick, at 124 mm:

Quote
Sandwich Composite Panels (http://static.monolithic.com/pdfs/thesis/quimby.pdf)
These panels, made of plywood on both sides with core insulation between them, were used in the construction of modular structures (living accommodation, kitchen, etc.)....  [T]imber frame was used and the panel thickness was 124 mm (12 mm thick marine plywood on each side and 100 mm core polyurethane foam insulation)...   [T]he floor needed additional insulation, because temperatures varied from -4C at the floor to 15C at the ceiling.

Just as baseline:

Polyurethane foam (http://www.madehow.com/Volume-6/Polyurethane.html) density is maybe 100 kg/m3.  Marine plywood, maybe 800 kg/m3.   If you double the South Pole foam thickness to handle rock conduction (enough?), the composite panel density becomes 176 kg/m3.

Result:  A cubic room 4 m on a side, with one open wall, would need 3 tons of insulation.

Not that you'd use those materials, obviously.  Other insulating materials are needed, via ISRU, and in bulk. 

Questions:  What can be made via ISRU, and how much is needed, to insulate that 4 m room?

(https://s-media-cache-ak0.pinimg.com/564x/df/bf/aa/dfbfaab786763c4c750b5c65a7d24a78.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2016 07:04 PM
The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 07:16 PM
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2016 07:44 PM
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Yes, but perhaps not necessarily through our load bearing walls, specially if they are full of ice, and that ice is part of the structural strength.
That being said, i'll admit I was just answering the problem posed by wstewart.  Hadn't really thought if there was a problem there in the first place  ;-)

If the thermal flow through the walls is too low, a very likely possibility in plant growing areas, then we might need active cooling.  I've recently done some grow rooms that had loads up to 1000 W/m2, so those needed refrigeration to be livable.  If we practice high intensity underground agriculture, and we probably will, then we may need to provide for some means of circulating a lot of heat and removing it to the surface to radiate away.  Or create sufficiently large heat sinks to have it absorbed by the soil.
I've heard enough stories about frozen geothermal wells though to know these might not be a very effective solution.  Melting ice and then letting it evaporate into the Martian air would probably be the simplest system.

Another possibility might be an equilibrium between underground heat gains and glass domes heat losses.  You can insulate the tunnels, to ensure a simple energy balance, in particular if you design simple domes with high heat losses, and then just use hot air to transport the heat around the base.  You would need to circulate the air anyway, for health, air treatment and plant growth reasons.





Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/26/2016 09:15 PM
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Any Mars habitat will have internal and external, active and passive heat sources, heat exchangers and heat sinks. These can all be carefully designed and tuned to produce robust thermal equilibrium. All fascinating things to talk about but maybe too far down in the weeds for the purposes of this thread! We can go back to envisioning amazing habitats and assume that there will be sufficient degrees of freedom to engineer robust thermal regulation for almost any (high level) habitat design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 09:26 PM
Light Bulb in the Freezer

Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

A wall-insulated Canadian basement at 4 m scale loses heat to the ground at a rate of roughly 600 W (http://web.mit.edu/parmstr/Public/NRCan/nrcc23378.pdf) (adapted from Appendix A). 

Comparison:  The uninsulated Mars room, sited within much colder ground, and with an extra ground-conducting wall, would lose heat at a rate well beyond a kW. 

Meanwhile the brave settler's body radiates only 100 W -- almost literally a light bulb in the freezer. 

Inference:  To attempt heat balance, we'd need insulation achieving more than an order-of-magnitude reduction in heat loss rate.  Two orders of magnitude might be a good starting point.

Addendum for Lumina: Unless that is, you want to just line the walls with many kilometers of heat exchange loops, and warm up the mountain for fun.  OPM!   :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/26/2016 09:33 PM
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 10:26 PM
Vacuum Tile?

The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.

So a... vacuum tile? 

If you can make a low-density basaltic brick with interior vacuum space, yeah, that might be a useful approach.  Glaze it front and back with low-e coating.  Add some press-and-click lattice mounting bracket to the back, for omnidirectional paving...  Hmm...   

What do you think?  Is there a method for manufacturing a low-density basaltic brick that can hold vacuum within?   And any idea what R-value (https://www.archtoolbox.com/materials-systems/thermal-moisture-protection/rvalues.html) you might end up with?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/27/2016 12:00 AM
Mars regolith would be much better insulation than Canadian soil due to the  near-vacuum.

Additionally, a dome will have a large footprint, which means for a given area, it will saturate the soil with warmth well before a Canadian basement would.

I agree with those who say insulating the ground will not be hard.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/27/2016 12:12 AM
Mars regolith would be much better insulation than Canadian soil due to the  near-vacuum.

Additionally, a dome will have a large footprint, which means for a given area, it will saturate the soil with warmth well before a Canadian basement would.

I agree with those who say insulating the ground will not be hard.

?  How do any of those assertions apply to heating of a pressurized rock tunnel room, the topic of the page?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/27/2016 06:24 AM
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Yes, but perhaps not necessarily through our load bearing walls, specially if they are full of ice, and that ice is part of the structural strength.
That being said, i'll admit I was just answering the problem posed by wstewart.  Hadn't really thought if there was a problem there in the first place  ;-)

If the thermal flow through the walls is too low, a very likely possibility in plant growing areas, then we might need active cooling.
I have done some interesting math on something related: A megawatt of waste heat deep under the ice could keep a sphere of water a kilometer across liquid at equilibrium. The temperature remains fairly stable regardless, a bit above freezing, instead the volume grows.

(That rabbit hole begins here:
http://forum.nasaspaceflight.com/index.php?topic=40628.msg1564606#msg1564606)

(however it is important to note that it would take thousands of years to reach that equilibrium.. A megawatt of energy is only about enough to melt a 170 tons of ice a day, and something a kilometer across is of the order of a billion tons)

This is potentially very useful, but also could make many underground concepts very unstable.

This is why I have a bunch of ideas similar to wstewart, though mine for the most part are pretty fuzzy.

Roughly they are:
* Deliberately create our waste heat underground (or under ice). Probably also direct sunlight there eg with light pipes.
* Live at a depth of about 30 meters, where there is robust 1atm pressure.
* Have a floating layer of some material lighter than water (it could for example be mass produced water filled bags with small air pockets) with a mass of around 1ton/m2. This will provide enough pressure to prevent water boiloff in average mars conditions.
* Dont rely on the strength of frozen ice or regolith, or in fact the strength of anything. Everything is ordered the way it should be by gravity.

You can start very small, even a curiosity sized rover could set up something like this before humans arrive. There is no real limit to the size it could grow to as more people arrive and create more waste heat. It could be a form of paraterraforming where a suburban city and ocean just grow together until it covers thousands of square km.. Also the same basic idea can be applied to any icy world from here out to the Oort cloud. Entire worlds could become oceans under protective eggshells of ice, so easily it might be an unintended consequence.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2016 06:59 AM
What do you think?

When Elon Musk has suggested, that digging caves would be an easy method of providing living space or space for production did he have people do some math on heat disspation and other potential problems like insulation or is it just a off the cuff remark?

My guess there is some careful deliberation behind it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/27/2016 07:45 AM
Re: Insulation in a tunnel.
You guys do realise that an inhabited space will need to get rid of heat, not retain it?
Meanwhile the brave settler's body radiates only 100 W -- almost literally a light bulb in the freezer.

So you expect the power consumed by colonists, by all systems inside the inhabited space, ECLSS, electronics, computers, growing areas, etc, will be... zero?

ISS uses about 25kW per person. Mir aimed for just over 10kW per person, but was severely underpowered at less than 5kW per person.

If a large base on Mars consumes less than 1kW per person, I will eat a space heater.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/27/2016 08:02 AM
What do you think?
When Elon Musk has suggested, that digging caves would be an easy method of providing living space or space for production did he have people do some math on heat disspation and other potential problems like insulation or is it just a off the cuff remark?
My guess there is some careful deliberation behind it.

Musk does tend to throw ideas around fairly off-the-cuff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/27/2016 01:11 PM
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.

This is a very important design point. As the dimensions of a habitat increase, heat loss to the environment increases as the exterior area. However, livable volume increases faster than the exterior area. So heat loss per unit volume of habitat decreases as the continuous habitable volume goes up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 11/27/2016 01:30 PM
Having the equipment to dig tunnels and caves to live in solves several problems, beyond low radiation habitations.  Those include mining for raw materials, initially water in large quantities, a place to store the water underground, possibly underground storage for oxygen and methane, and eventually mining for other industrial raw materials. There could be a vast network of interconnected tunnels and caves where people spend most of their lives. Kind of creepy, but more practical than having to put on pressure suits to go out all the time, especially for kids.

I think it may be practical to grow as much food as possible in greenhouses on the surface pressurized with Mars atmosphere, but would need a lot of automation since people would have to wear suits to work there as it will be mostly CO2 except for the O2 produced by the plants. They can provide supplemental lighting at night to allow 24/7 growth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2016 02:03 PM
Plants could not stand that much CO2. It would have to be a mix of CO2, oxygen, nitrogen plus argon as there would be a surplus of it from fuel production and it would do no harm. Probably still too thin for humans if you go for the minimum needed by plants. But if it is half of what humans need, it may be much easier to design counterpressure suits. They would need to span a smaller pressure difference and they would make working there much easier than spacesuits. Still mostly automated, I agree.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 11/27/2016 03:20 PM
Vacuum Tile?

The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.

So a... vacuum tile? 

If you can make a low-density basaltic brick with interior vacuum space, yeah, that might be a useful approach.  Glaze it front and back with low-e coating.  Add some press-and-click lattice mounting bracket to the back, for omnidirectional paving...  Hmm...   

What do you think?  Is there a method for manufacturing a low-density basaltic brick that can hold vacuum within?   And any idea what R-value (https://www.archtoolbox.com/materials-systems/thermal-moisture-protection/rvalues.html) you might end up with?
Microwave oven.

By Micowaveing the basalt regolith it can be formed in to a solid hard brick of any shape. It is also possible to do an additive process 3D printing that adds material while microwaving to create complex shapes with internal hollows. This equipment would take some significant development but would be an easy building material manufacturing system that does not require significant refinement process before use. A screening process to remove rocks. The finer the powder the better. The fine powder would enable smooth shapes and surfaces. A sandy consistency would probably have higher strength (maybe).

See the information about using similar process on Lunar regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/27/2016 03:41 PM
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.

This is a very important design point. As the dimensions of a habitat increase, heat loss to the environment increases as the exterior area. However, livable volume increases faster than the exterior area. So heat loss per unit volume of habitat decreases as the continuous habitable volume goes up.
Area goes up to the square and volume to the cube.  In general, of course.  Strain also goes up to the cube of the dimensions (or the square, I forget  :-(, so there is an optimal point between maximum volume and acceptable strain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/27/2016 08:10 PM
Hew Thermopylae - Draft 1

OK, taking a first shot at "Hew Thermopylae", a tunnel-hab that is notional only, and not much loved by the designer. 

For discussion.  Draft 1.  Hypothetical, very.



Quote
At length they drew near New Thermopylae; where, that same evening, Mrs. Hominy would disembark.  A gleam of comfort sunk into Martin's bosom when she told him this.  Mark needed none; but he was not displeased.
It was almost night when they came alongside the landing-place.  A steep bank with an hotel, like a barn, on the top of it; a wooden store or two; and a few scattered sheds.
"You sleep here to-night, and go on in the morning, I suppose maam?" said Martin.
"Where should I go on to?" cried the mother of the modern Gracchi.
"To New Thermopylae."
"My! aint I there?" said Mrs. Hominy.
Martin looked for it all round the darkening panorama; but he couldnt see it, and was obliged to say so.
"Why that's it!" cried Mrs. Hominy, pointing to the sheds just mentioned.
"That!" exclaimed Martin.
"Ah! that; and work it which way you will, it whips Eden," said Mrs. Hominy, nodding her head with great expression.

-Charles Dickens, "The Life and Adventures of Martin Chuzzlewit"




Working assumptions of this notional tunnel-hab:

Erebus Montes prospect (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613485#msg1613485) is the site.  Other ideas are welcome of course, but that's the most promising site my cursory prospecting has turned up.

Mesa UCS:  45 MPa

Safe pillar load:  16 MPa  (loosely inferred from Mathey and van der Merwe 2016 (http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2016000300015))

Pillar square side:  15 m

Gallery width:  6 m

Room height:  4 m



For the brave 300 of this Hew Thermopylae, we have the following rough design:

Image:  HewThermopylaeHypothetical1.png

General method of Roadheader room-and-pillar tunneling.

Image:  HewThermopylaeHypothetical2.png

Room-and-pillar living/working space.  One dormitory unit having 8 dorm rooms and a common space in center.

Image:  HewThermopylaeHypothetical3.png

Layout for 300.  Paired dorm units, with 5 east-west main hallways, repeated across 1.6 km.  3 equipment bays to N.  A pair of 600-m tunnels to S entrances.

Image:  HewThermopylaeHypothetical4.png

S exposure of the block mesa. 

Image:  HewThermopylaeHypothetical5.png

Hab plan overlaid on mesa.

Image:  HewThermopylaeHypothetical6.png

Google Mars perspective view of S exposure.  The two entrances are marked with blue squares.



"What about..."  Yeah, I got that thing totally wrong.  ;)  But just a few notes to start:

Total pressurized volume:  320,000 m3

Dorm room volume: 180 m3

Overall volume per resident, including common spaces and halls, excluding equipment bays and entranceways:  980 m3

Tunnels are cut with a pair of Sandvik Roadheader MR620 (http://www.miningandconstruction.sandvik.com/sandvik/0120/Internet/Global/S003713.nsf/Alldocs/Products*5CContinuous*2Dmining*and*tunneling*machines*5CRoadheaders**2D*tunnel*miners*2AMR620/$FILE/Brochure_MR620.pdf) equivalent machines.  With conveyors and other equipment, tunneling requires ~ 2 MW continuous power.  Assuming power is direct PV, tunneling is restricted to ~ 6 hours per sol.  Tunnels are completed in ~ 2000 days, or 5.5 Earth years.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 02:19 AM
"How to survive the winter?"

Previously lamontagne calculated heat flux through his insulated ovoid dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1605896#msg1605896).  I inferred that the dome's 22,000 m2 surface area would radiate heat at ~ 800 kW on a -90 C winter night.  How to survive the winter in that dome?  I recall we were thinking about layering thick insulation around the dome, or just abandoning it til spring.  (!)

At Hew Thermopylae the heating problem appears order-of-magnitude worse -- and winter bug-out isn't an option.  Hew Thermopylae living quarters have an order-of-magnitude more surface area, ~ 220,000 m2.  If the -60 C rock conducts a very hypothetical 38 W/m2, it could conduct out an order-of-magnitude more heat, at ~ 8 MW.

The spartan 300 produce a mere 30 kW of heat themselves, leaving a stubborn deficit of, still, ~ 8 MW. 

Maybe a heat exchanger could pump that 8 MW into the rock, if you had 8 MW of heat to exchange.  (And if you had an exchanger clever enough to avoid pipe freeze-burst at -60 C, when pumps glitch.)  You'd just need the 8 MW.  You'd need it in winter, when PV sits idle 18 hours per sol. 

So the 8 MW comes from... 

ah...

Well, the question again becomes, "How to survive the winter?" 

Absent a pricey and hot-blooded nuclear reactor, the need for insulation does seem critical here.  220,000 m2 of hab area needs coverage.  If you had a recipe for lamontagne's clever "vacuum tiles (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613644#msg1613644)", let's say, and each tile covers [x] and masses [y] and burns [z] Joules in fabrication... 

Hmm... 

[noodling]

(http://www.aljazeera.com/mritems/Images/2015/11/30/a3a17370d15d460f805e1150476246a9_18.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 02:55 AM
"How to survive the winter?"

Previously lamontagne calculated heat flux through his insulated ovoid dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1605896#msg1605896).  I inferred that the dome's 22,000 m2 surface area would radiate heat at ~ 800 kW on a -90 C winter night.  How to survive the winter in that dome?  I recall we were thinking about layering thick insulation around the dome, or just abandoning it til spring.  (!)

At Hew Thermopylae the heating problem appears order-of-magnitude worse -- and winter bug-out isn't an option.  Hew Thermopylae living quarters have an order-of-magnitude more surface area, ~ 220,000 m2.  If the -60 C rock conducts a very hypothetical 38 W/m2, it could conduct out an order-of-magnitude more heat, at ~ 8 MW.

The spartan 300 produce a mere 30 kW of heat themselves, leaving a stubborn deficit of, still, ~ 8 MW. 

Maybe a heat exchanger could put that 8 MW into the rock, if you had 8 MW of heat to exchange.  (And if you had an exchanger clever enough to avoid pipe freeze-burst at -60 C, when pumps glitch.)  You'd just need the 8 MW.  And you'd need it in winter, when PV sits idle 18 hours per sol. 

So the 8 MW comes from... 

ah...

Well, the question again becomes, "How to survive the winter?" 

Absent a pricey and hot-blooded nuclear reactor, the need for insulation does seem critical here.  220,000 m2 of hab area needs coverage.  If you had a recipe for lamontagne's clever "vacuum tiles (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613644#msg1613644)", let's say, and each tile covers [x] and masses [y] and burns [z] Joules in fabrication... 

Hmm... 

[noodling]


Well, we certainly don't want poor Thermpylae to die of cold.  The main answer depends on a question: do they produce their own food?  If yes, then they must produce it the way we do on Earth, through photosynthesis.  As we can find out easily, this is not a very efficient process, 2% for crop plants.  So our 100 Watts per colonist requires 100/0.02= 5 kW per colonist.  A gain of 50 is requires as an aboslute minimum.  A gain of 100 would be very good, IMHO.  So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth.  This is an absolute minimum, we haven't added any other processes, such as transportation, production of goods, air circulation, water circulation, etc.
 
The colony is in danger of heat death!  And this is because of absolutely unavoidable food production.  Suddenly these glass domes that lose a lot of heat are looking good...



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:09 AM
Any skeptics about vacuum tiles?

Just in case, I suggest a trip to Wikipedia: https://en.wikipedia.org/wiki/Multi-layer_insulation
or
A variation of this is the Vacuum insulation panel: https://en.wikipedia.org/wiki/Vacuum_insulated_panel
or
A third possibility is foam glass, that should be possible to produce in situ: https://en.wikipedia.org/wiki/Foam_glass

Mars atmosphere is practically a vacuum.  These should all work just fine.  Just pick your favorite.

But remember, any food producing underground base will want to get rid of heat.  So insulation may not be required, except for comfort near the walls.  And because the plants need the heat.

A Mars base is just a plant's way to get light and heat.  They will give you some seeds in exchange  :-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 03:15 AM
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:16 AM
A final point about thermodynamics of underground bases.  Conduction equation is Q=AdT/R.
dT is the temperature difference between the interior of the base and the soil.  R in the insulation value of the materials.
Now, as your soil heats up, the thickness of the warm soil around the base and the original cold soil gets thicker and thicker.  Eventually, you will have a few meters of warm soil, and it will now serve as insulation.

Any underground base that is sufficiently deep will reach an equilibrium where the heat loss becomes negligible, and eventually overheat.  The only exception is if the heat reaches the surface and starts radiating away.

The Earth is a perfect example of this. 12-20 km of Rock, with  an overall R value of many thousands, has been keeping the core hot for billions of years... (plus the radioactive materials in the core, of course). 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:19 AM
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 15 MW

in winter

at night

on Mars?


Insulate your base with the patented 'Lamontagne Tiles'.  No more heat loss ;-)  Produce twice the food you need in summer, as reasonable people do.  Eat the surplus in winter.  Since you are not producing food in winter, you are adding much less heat to your base.  Win-win.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:22 AM
You can also get a nuclear reactor.  They always solve everything. 
But solar only is so much more Fun!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:32 AM
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)
Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:35 AM
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.
And don't grow the food at night, never a good idea!
Robot is right, build the base with a lot of heavy walls, and a lot of water tanks.  It'll be both nicer, less noisy and have plenty of thermal inertia.  The surface swings up and down depending on the sun, underground, it's all smooth and calm...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:48 AM
Oh, and also, each refueling of a BFS requires approximately 0.5-1MW of power on average. Some of that power is lost as waste heat in the exothermic Sabatier reaction or inefficiencies of electrolysis. Because I'm too lazy to calculate, I'd bet it's around half of the power ends up as low quality waste heat that could be used for heating the colony space, just like waste heat from generators at the South Pole is used for heating, too. So 250-500kW per BFS

So if you have 100 BFS refueling every year, that's about 30MW of heat on average, plus the solar gain you get on that huge glass dome, etc. And with 1000BFSes, that's 300MW of heat. With 10,000 BFSes, 3GW of heat.

I think waste heat will be largely sufficient for base operations. In a pinch, you could burn some ISRU fuel, but it'd have to be an emergency.

Waste heat from ISRU, waste heat from photosynthesis (good call on the factor of 50, so about 5kW per colonist just in waste heat from inefficient photosynthesis), plus solar thermal gain from glass dome, insulation, and thermal inertia. I agree that rejected heat may end up being the more annoying problem long-term as the base grows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:02 AM
A final point about thermodynamics of underground bases.  Conduction equation is Q=AdT/R.
dT is the temperature difference between the interior of the base and the soil.  R in the insulation value of the materials.
Now, as your soil heats up, the thickness of the warm soil around the base and the original cold soil gets thicker and thicker.  Eventually, you will have a few meters of warm soil, and it will now serve as insulation.

Any underground base that is sufficiently deep will reach an equilibrium where the heat loss becomes negligible, and eventually overheat.  The only exception is if the heat reaches the surface and starts radiating away.

The Earth is a perfect example of this. 12-20 km of Rock, with  an overall R value of many thousands, has been keeping the core hot for billions of years... (plus the radioactive materials in the core, of course).

Right, ultimately you want the rock to stop being a heat sink, and start insulating.  Problem is, each m3 of rock soaks up ~ 200 million Joules on its way to room temperature.   Long road, deep mountain.  But it would be very interesting to see how the 1-D thermal profile under the hab room evolves over time, with various heat inputs.  Starting point is of course a stubborn -60 C.

Speaking of thermal profiles, maybe it's worth noting that the martian crust has a profile rather more cruel than Earth's.  Even an extremely deep hab, at 2 km depth, would be surrounded by rock at ~ -40 C, which is not very helpful.  A hab at equilibrium (in room temperature bedrock) would have to hit a sick depth of ~ 8 km.  A very diligent Sandvik MR620, running 6 hours per sol on a 10 degree cut, would need about 40 years to reach the front door. 

If it doesn't hit basalt.  :o
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 04:05 AM
Let's say we have 100 tons of material per colonist that is heated to room temperature. Assume it has a heat capacity of 1J/(gram*degreeC) (water has 4J/(g*C)). So that's 1E8J per degree C. So let's say we allow up to 20degreesC temperature change. That's 2E9J per colonist. Even if all power is cut, the whole thing is plunged into utter darkness and everyone's metabolism stops, that means if we have 1kW of heat loss per colonist, it'd take over 20 days to eat through all that thermal inertia.

Triple that if you also had 10 tons of water (or 40 tons of rock/sand) heated to near boiling by Sabatier waste heat (which is optimally 300-400C).
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:41 AM
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)
Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.

Thermal inertia from sunshine doesn't warm the winter tunnel.  We couldn't even manage solar heating of an insulated winter greenhouse, as I recall, which is why we had to abandon lamontagne's dome for the season.  But you might try heating water with winter flux, to see what you get.

As for batteries, flow batteries are presently state-of-the-art at this scale.  A 100 ton flow battery can deliver, I think, maybe 70 billion J of electrical heating.  At a 30 MW burn rate, that lasts half an hour.

How to survive the winter?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 08:37 AM
And don't grow the food at night, never a good idea!

Unless you have that nuclear reactor that wants to produce power day and night. You would probably want a set of greenhouses that are lighted in turns.

But why do I argue this? I am much in favor of greenhouses using mostly ambient light and maybe some added light for peak biomass production for some crops during part of their growth cycle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 11:54 AM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 12:04 PM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 12:38 PM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 02:39 PM
PV or not PV?

Just to quantify the winter PV problem at Hew Thermopylae:

1 ton of state-of-the-art PV produces ~ 100 kW, summer high-noon max.

Hew Thermopylae is at 34 N, where winter sunlight intensity drops to ~ 15% of summer max.

So in winter, that's 15 kW max, maybe 160 million Joules / sol. [corrected]

If that energy were stored and released on-demand with 80% efficiency, that's 130 million Joules/sol of heat energy.

And with a hypothetical 8 MW conductive heat loss, the uninsulated tunnels would need 700 billion Joules / sol.

So 5400 tons of PV, just for heat. 

(http://i.dailymail.co.uk/i/pix/2015/02/11/258E7F9500000578-2948238-image-a-5_1423625677289.jpg)

And assuming no winter storms (https://www.nasa.gov/mission_pages/msl/multimedia/vasavada-4.html).  :o
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/28/2016 02:55 PM
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat.
I'm not talking about astrobiology.

The equivalent of Martian Coal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/28/2016 03:06 PM
How to survive the winter?

Good old fashioned engineering and planning.

Once you have a Mars base with ISRU that produces breathable air, drinkable water, and food you are in pretty good shape. If a habitat design can't maintain a livable temperature, then it's time to design a different habitat. If a location can't produce enough solar power during winter, you need to pick a better location.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 03:20 PM
And his hydrogen comes from a bottle, gratis.

No it doesn't. Half of the hydrogen goes into water and needs to be recovered by electrolysis.

Edit: Some power is needed for controlling gas flow and pumping the process products but that is miniscule in comparison to the amounts produced.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:31 PM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:58 PM
And his hydrogen comes from a bottle, gratis.

No it doesn't. Half of the hydrogen goes into water and needs to be recovered by electrolysis.

Edit: Some power is needed for controlling gas flow and pumping the process products but that is miniscule in comparison to the amounts produced.

His hydrogen comes from a bottle.  In his shop.  Obviously electrolysis is required on Mars, pulling even more electrical power.  Point:  even the exothermic Sabatier reactor requires electrical power, continuously, by itself.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 05:18 PM
PV or not PV?

Just to quantify the winter PV problem at Hew Thermopylae:

1 ton of state-of-the-art PV produces ~ 100 kW, summer high-noon max.

Hew Thermopylae is at 34 N, where winter sunlight intensity drops to ~ 15% of summer max.

So in winter, that's 15 kW max, maybe 22 million Joules / sol.

If that energy were stored and released on-demand with 80% efficiency, that's 18 million Joules/sol of heat energy.

And with a hypothetical 8 MW conductive heat loss, the uninsulated tunnels would need 700 billion Joules / sol.

So 40,000 tons of PV, just for heat.


Isn't 15 kW x 3600s x 6 hrs = 324 million joules?  so 2000 tonnes rather than 40 000 tonnes?
If you stop food production and fuel production during winter, and insulate the base to a heat loss of 2 MW, then 500 tonnes of solar cells would be enough to keep you warm.  No reason you couldn't go bellow 2 MW with a well insulated base, and keep some production capacity going.

In summer, the cells would produce 6.6 times more energy, so 13.2 MW, enough for basic food production, then another 500 tonnes would produce 25 MW, enough food to pass the winter, and fuel for the ships.

If you had sun tracking solar panels, you could probably do better than these numbers; less mass or more energy.

And some of these powers are used twice, once for Sabatier fuel production, then, the lower grade losses can be used to heat the base, or again, 95%+ of the plant light turns into heat, that can also be used to heat the base.  So most of the time no heating load.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 05:22 PM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting

A Sabatier reactor is not a nuclear reactor.  It's chemistry:  net useful energy output < electrical energy input.  Losses occur at each step, and no practical design catches all the waste heat at each step.  So we minimize steps, ideally down to just one:  convert PV electrical power directly to heat, for example in a tunnel heating wire. 

But of course PV itself is a problem in winter, because there doesn't seem to be nearly enough (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614102#msg1614102). 

Disagree?  Well, you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 05:39 PM
If we need 25 MW of installed solar power to run a 300 person base, and these are about 0,1 kw per m2 (summer), then we need 250 000 m2 of solar panels?  A bit more than 500m x 500m?  does that seem about right? And a 10 000 person base would be about 3 x 3 km?  And the 1 million people target city 30 km x 30 km?

Most likely spread out among a number of smaller communities, or will Mars generate a single big city and a number of mostly robotic outposts?






Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:04 PM
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting

A Sabatier reactor is not a nuclear reactor.  It's chemistry:  net useful energy output < electrical energy input.  Losses occur at each step, and no practical design catches all the waste heat at each step.  So we minimize steps, ideally down to just one:  convert PV electrical power directly to heat, for example in a tunnel heating wire. 

But of course PV itself is a problem in winter, because there doesn't seem to be nearly enough (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614102#msg1614102). 

Disagree?  Well, you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see.
Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:13 PM
Where do the losses go? Waste heat. Which we can use.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:26 PM
Also build on the equator melas  and use lighter weight PV
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 08:01 PM

...you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see [net heat recovered for Hew Thermopylae].
 

Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct


Just try to sum the energies into and out of the Sabatier/electrolysis system (including heat lost and recovered), and then I think you'll ballpark the fraction of tunnel heat you get from Sabatier PV, relative to what direct PV heating can give.  Which itself isn't enough, but still.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 11/28/2016 08:11 PM
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 08:28 PM

...you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see [net heat recovered for Hew Thermopylae].
 

Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct


Just try to sum the energies into and out of the Sabatier/electrolysis system (including heat lost and recovered), and then I think you'll ballpark the fraction of tunnel heat you get from Sabatier PV, relative to what direct PV heating can give.  Which itself isn't enough, but still.
You still are attacking something I'm not saying.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 08:32 PM
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/28/2016 08:46 PM
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 08:47 PM
Isn't 15 kW x 3600s x 6 hrs = 324 million joules?  so 2000 tonnes rather than 40 000 tonnes?

It'd be ~15 kW at high noon, but it drops off after.  And I see I got the drop-off wrong.  Correction:  more like 160 million Joules/day, for 130 million Joules of useful heat at 80% conversion.  So maybe 5400 tons of PV.  All just ballpark.  Corrected above.

If you had sun tracking solar panels, you could probably do better than these numbers; less mass or more energy.

Actually I've read that stationary panels are doing well now at capturing off-axis light, without sun tracking hw.  So I just assumed that, and didn't allocate any mass for sun trackers.

... the lower grade losses can be used to heat the base...

Was wondering about that low-grade waste heat.  If it heats exchange-loop water to, say, room temperature, is that enough to prevent freeze-burst as the loop conducts heat into the cold rock?  Wouldn't we want water near boiling point in the loops?  But am unsure what temperature range you had in mind.

[Or maybe these things lead to sghill's other thread (http://forum.nasaspaceflight.com/index.php?topic=34836.400).]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 09:05 PM
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.
Meh, average temperatures even during winter are no worse than Earth South Pole during winter night. And Mars is near vacuum so lower thermal transfer rates
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 09:14 PM
Yurt?  Dirt?

We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.

Cold sure enough.  And yes, you'd scavenge heat wherever practical, sure. 

Actually I'm wondering if maybe the heating problem is so bad that it renders this tunnel-hab concept more trouble than it's worth.  "By an order of magnitude," even.   :)   -60 C rock is just such an excellent heat conductor, and when it surrounds the crew on nearly every side, day and night... 

Well, maybe Hew Thermopylae is just an exercise in "problems of Xtreme hab design," without a ready solution. 

Question:  Anybody vote to exit the mesa now, and apply our painful knowin' to more forgiving hab designs, outside?

(https://media-cdn.tripadvisor.com/media/photo-s/0d/70/1b/0a/aidar-yurt-camp.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 11/28/2016 09:14 PM
Enough about heat and power production. Don't do an offtopic post and link to another thread, just post in the other thread.

Thanks.

Edit: Heat is fine, agreed, heat rejection/generation/storage is important and doesn't have other homes at present. But any of the usual Nuclear/Solar is better/worse cheaper/costlier safer/dangerous-er stuff? Right Out.

Thanks
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/29/2016 03:57 AM
Enough about heat and power production. Don't do an offtopic post and link to another thread, just post in the other thread.

Thanks.

Thank you. Proposals for amazing habitat concepts - especially when paired with a specific proposed location on Mars - would be great additions to this thread.

(Edit: this thread should not concern itself with energy and heat sources. There are many options and degrees of freedom to solve any energy supply or thermal balance problem on Mars. For the purposes of this thread let's assume that energy/heat are solved and just go ahead to propose amazing hab concepts)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/29/2016 04:29 AM
There are no threads that concern chiefly with heat. This is the only one that really focused on it. Makes sense as heat management is one of the chief constraints of habitat design. I challenge the idea that it's off-topic here! Power, on the other hand, has like a billion cajillion threads devoted to it and isn't so directly coupled to habitat design (solar makes the most sense in vast fields and nuclear would be placed a safe distance from the habitat).

By the way. My keyboard was broken, so I wasn't able to properly respond. So let me do it now.

Musk has mentioned three habitats.
1) The ITS itself (clearly off-topic here)
2) Glass domes (has its own thread)
3) Tunnels (which seems to be the focus of this thread)

In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

What do we know about industrial equipment on Mars? The biggest (besides the off-topic power production) are:
1) Electrolysis of water
2) Sabatier reaction of water with CO2
3) possibly extraction of water from the soil, although it seems to me this is best done out on the surface

Any kind of energy-intense industrial process is going to have waste heat. And the easiest place to dump it is not the thin Martian air but the air of the pressurized industrial tunnels, even though they'll be at higher temperature than the outside air. Filling up the ITS in a synod is going to take about half to a full Megawatt of electricity. Most of that is losses and doesn't end up as methane chemical energy. So if you have a thousand ITSes refueled every synod, that's hundreds of megawatts of heat you get automatically for free. No extra power required. It's already needed.

In Minnesota, we sometimes get a week where it doesn't get above zero. And the wind is brutal, carrying any heat quickly from your body. But the Mall of America was designed entirely without a heating system. It relies entirely on waste heat from sunlight coming in the massive skylights, artificial lighting, internal equipment, and warm bodies. I think a Mars settlement would be similar.


I like the Sabatier reaction as an example because it operates at high temperatures and so you have more options about what you do with the waste heat. You can, for instance, put it deep within the regolith underlying the settlement. So deep that the heat pulse produced by summer's excess electrical capacity (dumped still in the Sabatier process) doesn't reach the surface until the middle of winter when it's needed most. So the regolith itself is acting as a reservoir of heat and a sort of delay buffer to even out the heat flow.

And you don't need to really worry about pipes freezing. It's likely you'd use ethylene glycol or propylene glycol for the heat loop. Both are fairly easy to make via ISRU. Or even methanol. And the deep soil is already naturally at a high enough temperature to prevent freezing in that case. And even more so once you've dumped any kind of significant amount of heat into the soil. The ground will stay relatively warm for years.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/29/2016 05:13 AM
Quote
In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

I have experienced first hand how just a spring melt can cause an otherwise relatively safe mine to become active and worthy of concern.  Even several hundred feet below a mountain, water finds it way into the mine and can cause minor to major cave ins.  Granted water will not be the issue on mars, but changes caused by heat may well be.  If your plan is to constantly pump heat into tunnels, I hope you aren't planning on making those places habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 07:14 AM
Siting Industrial Equipment For Habs

Quote
In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

I have experienced first hand how just a spring melt can cause an otherwise relatively safe mine to become active and worthy of concern.  Even several hundred feet below a mountain, water finds it way into the mine and can cause minor to major cave ins.  Granted water will not be the issue on mars, but changes caused by heat may well be.  If your plan is to constantly pump heat into tunnels, I hope you aren't planning on making those places habitats.

Tunnel-hab is not my preference, no.  You wouldn't have spring melt, but I imagine the walls might "sweat" when heated.  Could get messy -- or messier.   :o

If these pressurized tunnels aren't used as habs, but only as equipment bays, why build them?  Why not just design the industrial machines to work on the surface, perhaps in a pressurized cargo module, perhaps under a loose protective tent?  What could justify the great expense and difficulty of the dig, if inhabitation isn't the goal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 09:52 AM
Don't want to live in holes?  Here is Megatower!

1 km high.  Self supporting through air pressure, megatower has an external pykrete skeleton made up of 3 free standing columns than serves as backup if the internal pressure is lost. Internal arrangement is independent from the outer shell.

Megatower is protected from radiation by a minimagnetosphere that cover about 10 km2.  The little white smudge besides the tower is an ITS spaceship.  The slightly larger shape is a pickle type tower.

Each core is 60m in diameter and weighs 25000 tonnes.  It is supported by the air pressure exerted on the dome at the top of the tower.  The windows are light polycarbonate, the structure composite.

The pykrete columns are water and sand, reinforced with basalt fiber rods.  Wind loading is negligeable despite the structure's size.  As the columns are exterior to the habitat, they do not melt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 01:33 PM
Oz Beneath the Magnetic Cloud of Protection

Don't want to live in holes?  Here is Megatower!

1 km high.  Self supporting through air pressure, megatower has an external pykrete skeleton made up of 3 free standing columns than serves as backup if the internal pressure is lost. Internal arrangement is independent from the outer shell.

Megatower is protected from radiation by a minimagnetosphere that cover about 10 km2.  The little white smudge besides the tower is an ITS spaceship.  The slightly larger shape is a pickle type tower.

Each core is 60m in diameter and weighs 25000 tonnes.  It is supported by the air pressure exerted on the dome at the top of the tower.  The windows are light polycarbonate, the structure composite.

The pykrete columns are water and sand, reinforced with basalt fiber rods.  Wind loading is negligeable despite the structure's size.  As they are exterior to the habitat, they do not melt.

Pykrete, it's not just for aircraft carriers (http://www.discovery.com/tv-shows/mythbusters/about-this-show/what-is-pykrete/) now?  :)  And the facility is a lovely form, very Oz!  8)

As I understand it, pykrete gets its essential strength and low thermal conductivity from wood pulp fiber.  And I can understand why you might not want to ship pulp, and reinforce instead with ISRU basaltic fiber rods.  But why replace pulp with sand?  Wouldn't sand raise thermal conductivity significantly, without strength benefit?  Summertime seems challenging, with sand forcing measurable ice melt / sublimation on the columns, on those days when the surface regolith (sand) can exceed 20 C.

As for the magnetosphere, are you considering the notional balloon-encapsulated variant on Bamford et al. (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1604130#msg1604130), or something else?  If you go with an encapsulated form, can you add such a form to the illustration?  Should be a conversation-piece:  "Oz Beneath the Magnetic Cloud of Protection".   ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/29/2016 01:51 PM
Don't want to live in holes?  Here is Megatower!

Now that's "Envisioning Amazing Martian Habitats" on a grand scale.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 02:13 PM
Oz Beneath the Magnetic Cloud of Protection


Pykrete, it's not just for aircraft carriers (http://www.discovery.com/tv-shows/mythbusters/about-this-show/what-is-pykrete/) now?  :)  And the facility is a lovely form, very Oz!  8)

As I understand it, pykrete gets its essential strength and low thermal conductivity from wood pulp fiber.  And I can understand why you might not want to ship pulp, and reinforce instead with ISRU basaltic fiber rods.  But why substitute pulp with sand?  Wouldn't sand raise thermal conductivity significantly, without strength benefit?  Summertime seems challenging, with sand forcing measurable ice melt / sublimation on the columns, on those days when the surface regolith (sand) can exceed 20 C.

As for the magnetosphere, are you considering the notional balloon-encapsulated variant on Bamford et al. (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1604130#msg1604130), or something else?  If you go with an encapsulated form, can you add such a form to the illustration?  Should be a conversation-piece:  "Oz Beneath the Magnetic Cloud of Protection".   ;)
I'll go with SGHill's brilliant "the towers are an electrode". They are grounded at a ring all around the living area.  As the towers are 1 km high, why not a 2 km ring, so about 12 km2 of protected area.
The dust plays the role or rock and the water of cement in this Martian Pycrete.  We can paint the towers so they don't get too hot, and perhaps avoid this design in the areas that actually get a bit hot in summer.  Thermal inertia should do the rest to keep these cold.  In needed, they can be replaced by steel columns, but this should be cheaper.  Admittedly, concrete vs steel is always controversial with my structural friends.  Just imagine the columns made of your favorite material, doesn't change the concept.
About 3 000 000 m2 or 30 000 000 ft2 for the complex.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 02:23 PM
Would the minimagnetosphere be visible at night, rather like aurorae in northern climates?  In particular during solar storms?  then it would really look like Oz!  I expect during the day sunlight will be much to strong, and the minimagnetosphere would be invisible?

The ring might be a number of grounded rods, not a physical ring made of regolith?  Is the tower the emitter/ioniser, or is it the other way around?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 02:33 PM
Also, if you do go with some variation on Pykrete in the columns, you might consider adding ISRU gypsum to the ice, to lower thermal conductivity and give the ice a better chance of withstanding summer.  Mix some copper ions into the gypsum and you'll get the Oz coloration for your illustration.  L2!   8)

(https://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Gypsum-71006.jpg/314px-Gypsum-71006.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/29/2016 02:47 PM
Lar,

To be fair to Chris (Robotbeat), he wasn't actually talking about power production. That was just Wstewart insistently missing his point.



Don't want to live in holes?  Here is Megatower!
[...]

I like the audacity, but no. Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient. The volume required for internal transport alone would kill your concept.

However, if we're doing unlikely but interesting, how about a hanging-habitat. A giant, multi-kilometre single span "dome", with the habitats hanging vertically from the roof like icicles. Largest (longest) habitat at the centre, pulling the dome-roof down to create more of a pillow shape; with smaller habitats hanging around it, creating a dimple-pattern as they also weigh down the roof.

Spaced and aligned correctly, you should still be able to plant crops on the ground level without excessive shadowing from the hanging-habs.

Variation: A strip habitat. Similar to a tube-tunnel concept you did before, but on the surface. The bulk of the two strips of buildings providing the mass-anchor for the hemi-cylindrical roof spanning between them. Aligned east-west lengthways, with just enough leanback on the habitat-buildings to prevent shadowing during summer/winter solstice. (So as the equator, the habitat-buildings are symmetrically tilted 25 degrees away from the centreline. At 30 south, the northern strip is tilted 55 back, while the southern side can be vertical. (Hence the northern buildings are lower/smaller.) The east/west caps are quarter-spheres.

(Crude pic of the latter)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 03:08 PM
Lar,

To be fair to Chris (Robotbeat), he wasn't actually talking about power production. That was just Wstewart insistently missing his point.



Don't want to live in holes?  Here is Megatower!
[...]

I like the audacity, but no. Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient. The volume required for internal transport alone would kill your concept.

However, if we're doing unlikely but interesting, how about a hanging-habitat. A giant, multi-kilometre single span "dome", with the habitats hanging vertically from the roof like icicles. Largest (longest) habitat at the centre, pulling the dome-roof down to create more of a pillow shape; with smaller habitats hanging around it, creating a dimple-pattern as they also weigh down the roof.

Spaced and aligned correctly, you should still be able to plant crops on the ground level without excessive shadowing from the hanging-habs.

Variation: A strip habitat. Similar to a tube-tunnel concept you did before, but on the surface. The bulk of the two strips of buildings providing the mass-anchor for the hemi-cylindrical roof spanning between them. Aligned east-west lengthways, with just enough leanback on the habitat-buildings to prevent shadowing during summer/winter solstice. (So as the equator, the habitat-buildings are symmetrically tilted 25 degrees away from the centreline. At 30 south, the northern strip is tilted 55 back, while the southern side can be vertical. (Hence the northern buildings are lower/smaller.) The east/west caps are quarter-spheres.

Ha!  I was expecting that one!  The towers use the latest elevator technology from ThyssenKrupp
http://newatlas.com/thyssenkrupp-magnet-drive-elevator/34976/
to allow for multiple elevators in a single shaft, therefore reducing the transportation issues.  Actually not quite the latest, more like the slightly in the future...
The cylindrical shape reduces strain of the outer pressure membrane, exactly like vertical propane tanks you find in service centers. Horizontal circulation is also a space issue, at this scale, so I'm not convinced that kills the tall tower concept.
Now, the internal structure where people would actually live might be a problem.  I chose a 60m diameter because that can be subdivided into a 20m external ring, where you live, and a 20m core, for work, transportation and a rigid sway prevention construction.  It's probably a little wide, and a 40m cylinder might be more appropriate.

I like the idea of weighing down a dome with the habitat.  This reduces the strain on the attachments to the ground, since if it was perfectly balanced it no longer needs anchoring at all, but substitutes a requirement for a much stronger dome structures.  there might be an interesting compromise, with a dome supporting an internal donut type structure?  The donut would be supported like a suspension bridge by the dome.  I have my doubts we could be able to transmit the loads evenly, but perhaps if we had a lot of cables?  A kind of ring shaped suspension bridge!  But not certain this would be lighter than a tall tower.  alternatively, we could have a centrally supported cantilever structure that weights down on the edge of the dome.  Would have to be pretty thick though, but would give the living area structure a dual purpose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/29/2016 04:44 PM
Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient.
[...] The cylindrical shape reduces strain of the outer pressure membrane, exactly like vertical propane tanks you find in service centers.

But what is the advantage of going straight up compared to a similar structure parallel to the ground? There's effectively no limit to the length. Your buildings are impressive because they are 1km. A 1km long street of low buildings is, by contrast, considered trivial.

"Tall" only makes sense when land is limited. (Or when you're trying to project an image.)

Horizontal circulation is also a space issue, at this scale, so I'm not convinced that kills the tall tower concept.

It's a lot more energy efficient to move horizontally than vertically. Contrast walking along a flat path with climbing stairs in a building.

Also contrast how many people you can fit on a path, and how free you are (even when it's packed) to choose your own movement, compared to elevators in a building (even fancy neo-paternosters.)

I like the idea of weighing down a dome with the habitat. [...] but substitutes a requirement for a much stronger dome structures.  there might be an interesting compromise, with a dome supporting an internal donut type structure?

Hence the latter version. (Although semi-cylinderical, not a dome. Not very clear in my sad little cross-section. I'll admit, I was hoping you'd 3d it.)

I was also wondering about a ziggurat type structure, with bubble canopies around each row, with a small dome cap. The bulk of the structure is compressive (made from local materials, stone or sinter-crete), which provides the anchor-mass for the bubbles & cap.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 11/29/2016 05:33 PM
Did anyone mention a torus yet? Doesn't have the problems of lots of empty space like a dome, and with e small diameter, the pressure shouldn't be too high. Effectively the long thin horizontal structure from previous post, but with the ends joined together.

You could have concentric tori with a small dome in the middle. To make the 'city' bigger, add an extra torus round the outside.

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/29/2016 07:34 PM
But what is the advantage of going straight up compared to a similar structure parallel to the ground? There's effectively no limit to the length. Your buildings are impressive because they are 1km. A 1km long street of low buildings is, by contrast, considered trivial.

"Tall" only makes sense when land is limited. (Or when you're trying to project an image.)
I think projecting an image is one reason. IMO there are enough advantages to have at least some towers, if just to show what a tower on Mars can look like.

Possible advantages over horizontal cylinders.
*Better radiation protection (except for the top stories)
*Better views for the same window area. More panorama, less straight up: a direction we do not often look.

It might also be stronger as the weight helps resist pressure, and horizontal cylinders deal with varying directions of force based on pressure and bracing against varying ground. We might be able to design something that can be assembled floor by floor without cranes, in which case it is probably less fiddly to build a wider radius (say 50m) cylinder facing straight up than on the ground.

But sure. Cylinders on the ground will probably be our staple. Lots of advantages of these over towers too, such as being able to run for kilometers in a straight (or curved) line in a very natural possibly valley like environment. Could have a stream too.

(edit) Not directly on topic for towers, but I think wherever we live should encourage a fair bit of vertical movement. This would increase exercise and impacts. We can comfortably live in 2 story dwellings on earth, so maybe on mars we should aim for 5-6 story movement fairly common throughout the day.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 07:54 PM
Charge and Discharge

The thin, ultra dry atmosphere will hold a massive charge that can be created using specially shaped towers and the martian wind (think huge van de graaff generators) connected by a huge loop antenna that encompasses the colony.

Hmm...  Harrison et al. 2016 (http://link.springer.com/article/10.1007/s11214-016-0241-8) notes the Tripathi et al. 2008 (http://home.iitk.ac.in/~snt/pdf/Space_Sc_Review.pdf) finding that the martian atmosphere's "electrical conductivity is usually two orders of magnitude greater than that for Earth".  And Youngquist 2009 (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090022229.pdf) worries about his proposed shield's "difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge [emphasis added]." 

And that's in the space environment, with negligible electrical conductivity.   

Earth's atmosphere has higher electrical conductivity. 

And Mars, 2 orders of magnitude higher than Earth (~ 10-10 Ohm-1m-1).

Generally speaking, higher conductivity leads to faster electrical discharge.

So, question:  How to prevent rapid discharge (failure) of the shield on Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 11:42 PM
Did anyone mention a torus yet? Doesn't have the problems of lots of empty space like a dome, and with e small diameter, the pressure shouldn't be too high. Effectively the long thin horizontal structure from previous post, but with the ends joined together.

You could have concentric tori with a small dome in the middle. To make the 'city' bigger, add an extra torus round the outside.

Here is a surface version of an earlier underground tunnel version of the city.  Construction goes on forever in a continuous motion, side connectors make cross connections easier.  In a way this is typical of many of the forums... ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/30/2016 12:19 AM
I think a Ziggurat is interesting.  Gave it a go for fun.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/30/2016 12:28 AM
Cutaway view of a Dome inside a dome.  The green dome would be tied down to the white dome using cables.  This reduces the anchoring required at the base of the green dome, spreading the load.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/30/2016 03:43 AM
You can also have tension cables inside a single dome to spread the load. Much simpler than concentric domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/30/2016 10:44 AM
Cutaway view of a Dome inside a dome.

The outer white dome could be terraced for growing. (Irrigate at the top for high-sun, high temp, tropical crops; lower sun temperate crops further down.) The outer ring of ground between the outer white dome and the green pressure dome could be for aquaculture/algae-growing/water-treatment&recovery/thermal-dampening. Livestock in the central area (along with general purpose open space). Hab, production/processing, and storage then goes between the two white domes, and under the inner white dome. (You might have production facilities, labs, storage, etc, between the domes, with living areas under the inner dome with views of the central area.

IMO, your design makes better use of the upper volume than a conventional dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/30/2016 11:22 AM
The Obligatory Truncated Octahedron Stack

No one has said "truncated octahedron" yet.  So:

(https://lh3.googleusercontent.com/-Cnz6EsSKcNQ/T5_e46hGFTI/AAAAAAAAJds/bkfzmt_U4vI/s506/600px-HC-A4.png)

Or we can look at other polyhedral stacks, such as:

(https://maxwelldemon.files.wordpress.com/2012/03/cathedral.png) (https://maxwelldemon.com/2012/03/26/the-2x1-rectangle-and-domes/)

Pros of truncated octahedra:

- No tunneling.   ::)
- Few anchors.
- Modular, with typical geodesic flat-pack efficiencies. 
- Octahedron (maybe 5 m scale) approximates a sphere, for pressure-vessel mass-efficiency.
- Multi-level space-filling stacks further improve mass-efficiency.  Insulated pressure walls are installed on exterior rooms only.   Common walls would be thin and uninsulated, a bit like a beehive's efficient honeycomb interior.
- As settlement grows incrementally, exterior rooms are over-stacked to become interior rooms.  The over-stacked pressure panels are then replaced with thin interior panels, and the hab's net mass efficiency improves with growth.
- Top-level octahedra are modular roofing, filled with sand or water for alternating radiation shielding:  sand over sleeping quarters for max shielding, water over gardens and common areas, for light (maybe 50% transmission with transparent, lensed and reflective panels).
- Enlarged common area and garden "hollows" ~20 m scale should be feasible with supplemental open-frame truncated octahedra.

Cons:

- The usual geodesic issues, I guess. 
- Maybe just too dense and noisy.  Who really wants to live in a beehive?



Addendum:  A real-world example of space-filling polyhedric architecture, on similar scale:  Zvi Hechers Ramot Polin Housing Complex (http://inhabitat.com/zvi-hechers-hivelike-ramot-polin-housing-complex-is-an-ambitious-failed-experiment-in-israel/zvi-hecker-ramot-housing-1):

(http://assets.inhabitat.com/wp-content/blogs.dir/1/files/2013/12/Zvi-Hecker-Ramot-Housing-2.jpg)

Quote
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

And that kid's stereo, no doubt.

Theme and variation: Zvi Hecker's Polyhedric Architecture (http://www.zvihecker.com/projects/polyhedric_architecture-257-1.html)

And a bit of architectural math, explaining why one might want to stack truncated octahedra, generally:  Simplicity is Not Simple:  Tesselations in Modern Architecture (https://www.maa.org/sites/default/files/pdf/upload_library/22/Evans/september_2002_5.pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/30/2016 05:02 PM
Don't want to live in holes?  Here is Megatower!

It seems that one has to presuppose that there is an advanced industrial society on Mars numbering in the hundreds of millions to be on topic in this thread.

Or is that just me? :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/30/2016 08:52 PM
Well I for one am certainly not a vast industrial society numbering in the millions  8)

The Obligatory Truncated Octahedron Stack
No one has said "truncated octahedron" yet.  So:
Im interested in space filling polyhedra approaches.
https://forum.nasaspaceflight.com/index.php?topic=41526.msg1611256#msg1611256

I also thought I had linked to this somewhere.. but couldn't find it:
https://en.wikipedia.org/wiki/Honeycomb_(geometry)

There are options other than truncated octrahedron, for example the simple cube or hexagonal cylinder like we are used to from isometric games. I mean you wouldn't actually use a cube with those huge flat faces, but your internal struts could be a cube and each face could bulge outwards, perhaps like interlocking spheres. Or maybe they actually are flat but reenforced with internal cables.

I think these could actually give very interesting internal volumes by removing some internal faces.

One problem is that it would be nice to have faces that could resist pressure failure on either side.

If you can solve this I think it is a very attractive idea. Start small and just keep growing while accumulating more shielding and more redundancy.

I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/01/2016 12:07 AM
Don't want to live in holes?  Here is Megatower!

It seems that one has to presuppose that there is an advanced industrial society on Mars numbering in the hundreds of millions to be on topic in this thread.

Or is that just me? :)
It's just you :-))
There are many example of smaller buildings in the thread, giant buildings just evolved recently.  Size is an easy way to produce an  amazing effect, and it's interesting that Mars will eventually allow for the construction of larger buildings than on Earth.  However, clever and small can be amazing as well.  It's just harder to do.

A very specific Mars problem is that buildings have to be either extremely heavy, meaning many meters thick, to be in compression, or they need to be tension structures, which is essentially reserved for vehicles on Earth, or a few rare specialty structures.  This impacts the construction in various ways that are being explored. 

The radiation protection function is also something that doesn't exist on Earth.  This may or may not be an absolute, as mini magnetospheres are a possible alternative to mass shielding, and they have been mentioned by Musk as a possible solution.

The question of direct solar vs indirect solar has been touched upon, but not explored in detail yet.  Is it better to create a large array of solar cells, and use electricity and artificial lighting to grow plants in constant and controlled conditions, or to use greenhouses dedicated to plants or use a mixed construction, that integrates food production with habitat? Do these solutions change with latitude, as they do on Earth?



Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/01/2016 03:34 AM
Problems in Xtreme Tinkertoy

There are options other than truncated octrahedron, for example the simple cube or hexagonal cylinder...

Sure, I was just noting its useful properties.  For example, having highest volume to surface area could save some cargo mass (11% relative to cubes).

I think these could actually give very interesting internal volumes by removing some internal faces.

One problem is that it would be nice to have faces that could resist pressure failure on either side.

If you can solve this I think it is a very attractive idea. Start small and just keep growing while accumulating more shielding and more redundancy.

It's an old idea, but yeah, maybe its mass efficiency and shielded modular growth model can justify further thought.  Plus it looks better than a design-reference dirt pile.   ;) 

Thinking about materials: 

- Pressurized panels might be mm aluminum-lithium alloy, as on Orion. 

- Unpressurized exterior panels, like those on sand shield octahedra, could be thinner alloy. 

- Unpressurized interior panels could be ISRU high-density plastic.

- Lightly pressurized transparent panels, like those on water shield octahedra, might be 2x100 micron ETFE foil.  Garden 60 kPa pressure would counter each octahedron's water weight and 40 kPa interior pressure, to maintain a flat ETFE base panel for the sunlit water "ceiling". 

Low-mass panel materials like that, coupled to the geometric efficiencies, could make for a very mass-efficient system.  But of course the struts would be complex.  Struts and vertex connectors would have to be very cleverly designed, to enable easy pressure-vessel construction, panel replacement, high reliability, etc.  I suppose they'd also serve double-duty as modular universal conduits for air, water, power, etc.  Plus they'd have to handle a wide range of loads, as the facility goes through its various growth reconfigurations. 

That's not Tinkertoy easy, but it's not impossible, I think.

(https://libraries.mit.edu/digital-archives/files/2012/10/cropped-TinkerToy_computer_MIT.jpg) (http://museum.mit.edu/nom150/entries/1215)
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/01/2016 01:17 PM
Let's be real clear here.

"Domes" can't exist on Mars unless they are unpressurized.  There's no amount of downforce that's going to keep the air inside from "burping" out along the bottom like a gigantic whoopie cushion unless the dome is really a deformed sphere pressure vessel where the top is sealed to the bottom.

We've covered this in excruciating detail starting here:  https://forum.nasaspaceflight.com/index.php?topic=34667.msg1352100#msg1352100  and going on for about 15 pages. 

I'm particularly proud of my own post here: https://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550

 ;D

The whole discussion is a pretty good read for those of you who weren't participating in the chatter back then.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/01/2016 01:44 PM
Let's be real clear here.

"Domes" can't exist on Mars unless they are unpressurized.  There's no amount of downforce that's going to keep the air inside from "burping" out along the bottom like a gigantic whoopie cushion unless the dome is really a deformed sphere pressure vessel where the top is sealed to the bottom.

We've covered this in excruciating detail...

Long thread, categorical statement.  Just curious: did you see any force-analysis issue previously that would "burp out" Thistle Dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957)?   I haven't seen a force problem with the water seal myself.  It still seems workable through active pressure equalization.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/02/2016 03:39 AM
The Red Sands Saloon, our motto:  Wipe yer damn feet!
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 12/02/2016 10:07 AM
The Red Sands Saloon, our motto:  Wipe yer damn feet!

Make that concentric tori - avoid the pressure awkwardness at the corners.

http://www.toysrus.com/graphics/tru_prod_images/Imaginarium-Stacking-Ring--pTRU1-16548595dt.jpg
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2016 10:56 AM
The Red Sands Saloon, our motto:  Wipe yer damn feet!

Make that concentric tori - avoid the pressure awkwardness at the corners.

http://www.toysrus.com/graphics/tru_prod_images/Imaginarium-Stacking-Ring--pTRU1-16548595dt.jpg
Could be a bit tempting for some martian to come along and start playing Tower of Hanoi :)

There might not be a problem. It depends. The 4-sided structure is not that far off a set of spherically ended cylinders.

The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape. You could build up any shape sort of like in MineCraft, and it would not lose huge efficiency.

I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres. I mean, within some moderate fraction. Obviously once you start joining all these smaller volumes they are no longer exactly pure spheres etc.

In the case of space filling polyhedra the strength is in an internal set of struts, sort of like an aerogel, not just in a mathematically optimal surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 02:26 PM
The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape.

Is that still true once you start removing internal walls?

Quote
I don't think there is any loss of effectiveness from not having a large dome either.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres.

However, the materials themselves have non-linear scaling effects. For example, there's a minimum size in shell thickness before you lose so much strength in every other direction that the structure can't be trusted. (Just as basalt or glass becomes a flexible fibre below a certain thickness instead of a rigid but brittle solid. Any rigid frame elements will turn to wet-noodles once the struts get thin enough.)

That would suggest there's an optimal diameter for any particular material (which will be smaller if we're using a space-frame vs a solid shell), above the point where the thin-shell effect is replaced by the bulk properties. Either the minimum size where you stop gaining any strength/mass advantages, or the smallest size large enough to be useful. Any larger than that, and you might as well use multiple units; any smaller and you run into scaling issues.

In the case of space filling polyhedra the strength is in an internal set of struts, sort of like an aerogel, not just in a mathematically optimal surface.

The "internal" frame also gives you somewhere to hang your living space from. That gives you more usable internal volume. Domes tend to waste space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 05:40 PM
The Red Sands Saloon [...]
Make that concentric tori - avoid the pressure awkwardness at the corners.

That's my fault. I meant circular tiers when I suggested it, but called it a "ziggurat" which generally (always?) have square tiers.

http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614432#msg1614432 (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614432#msg1614432)

[Woah, why did my first pic get 275 views? There's no scale-hidden detail. It makes sense with TripD and Lamontagne's cool 3d stuff, but why did over 200 people need to enlarge or download my crappy paint.net drawing? Normally it's less than ten for such a simple sketch, presumably people browsing on their phones. Feeling a bit weirded out and paranoid.]

The Red Sands Saloon, [...]

In addition to JamesH65 point that it's supposed to be round, my suggestion of a ziggurat assumed a fairly flat location. That back side will be in permanent shadow, the right side not much better.

If you were against a slope, a hill or crater-wall, you'd just build essentially one (flat) face of the ziggurat against the slope.

[That also makes the structure more scalable, you can add new tiers, as well as extend tiers. (One of the things I don't like about my suggest ziggurat, it would need to be completed before it can be pressurised. There's no ability to expand organically once it's done.)]

Additionally, remember the point of the ziggurat is that the rock/sincrete structure serves as the anchor mass for the pressure vessel(s). Hence both the toruses and cap-dome must have an tangential angle of their anchors that points into the mass.

Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.

Flip-side, the tangent of the anchors of the cap-dome only needs to match the angle of the overall structure, as long as it's set back far enough for the line to run through rock/etc from top-to-bottom.

[Nonetheless, I realised I screwed up. The whole point was that the ziggurat is also an occupied space. But pressurising a stone/sincrete structure puts all the load on the outer walls. The toroidal bubbles and cap-dome together function as if they were a single dome over the entire volume, allowing you to pressurise the whole ziggurat, but then the tiers allow (indeed require) the skin that anchors at that point to bubble outwards at a greater angle, creating the toroidal effect. But I realised later that the anchors for the toroids/dome have to lock the ziggurat together anyway. So there's no advantage in having the bubbles, except for creating a bit of open space outside each tier.]

[Edit: I also screwed up the conical anchor mass on the second image. The anchor-mass of a rock anchor is an upward facing cone. Still gives the general idea, hopefully.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/02/2016 06:26 PM
Quote
Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.

Yah,  I have been assuming that all pressure response was built into the framework of the cylinders/partial spheres such that the square tiers were only there to provide easier architecture.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 07:26 PM
Quote
Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.
Yah,  I have been assuming that all pressure response was built into the framework of the cylinders/partial spheres such that the square tiers were only there to provide easier architecture.

My whole point of suggesting a ziggurat was that the structure serves as an anchor mass for the pseudo-dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2016 10:55 PM
The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape.

Is that still true once you start removing internal walls?

No it does break down a bit: I did note that here:
Obviously once you start joining all these smaller volumes they are no longer exactly pure spheres etc.

However I am imagining most of the strength being in internal struts that would remain even when you remove internal walls. You are not trying to save on mass or strength or cost by removing these internal walls, just trying to make it easy to wander from cell to another. The only savings you could get is that internal struts might be cheaper than window for the same strength.

It is a different question whether you could have larger internal atriums without even these regular struts. Then the overall shape begins to become important again. I think you would consider these larger areas as a different embedded cell design entirely rather than just assuming you can begin omitting struts when 3 layers deep etc.

(about this idea, I like it but a big hole is that I don't know what internal walls that can take pressure loss from either side would look like)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/03/2016 03:27 PM
I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres.

The radiation shielding doesn't scale with volume. That is obvious for passive shielding, but to my knowledge also holds for magnetic shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/03/2016 10:27 PM
The radiation shielding doesn't scale with volume. That is obvious for passive shielding, but to my knowledge also holds for magnetic shielding.
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes. Or underground but that is way off topic. Minimising heat loss might be a reason to keep things dome-like.

My point was only that cellular design could let you build to all sorts of shapes when considering pressure vessel cost. Of course there are other design factors that will affect what shape you choose, and a cellular design lets you pursue them.

Simplistically, you probably do pay a bit more for the cellular approach vs perfect spherical vessels. This is equivalent to whatever the structural mass is for a single cell compared to a perfect sphere of the same volume. But manufacturing giant spheres that cannot be used until completion and have no redundant protection also have costs and disadvantages. You also can't build different radii without different wall thicknesses. My guess is that a cellular design ends up cheaper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/05/2016 12:54 AM
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume), the optimal shape for magnetic shielding is a torus, to my knowledge.

But manufacturing giant spheres that cannot be used until completion and have no redundant protection also have costs and disadvantages.

I would expect early colonists to live in large inflatable habitats covered with soil, not in giant transparent domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/05/2016 01:58 AM
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume)...

For omnidirectional radiation, yes.  As in a tall tower, or in transit. 

Not the case at ground level of course, where the radiation of interest is directed downward.  In a circular surface plan, depression or excavated column, the optimal shape for shielding is a horizontal circle:  e.g., a shallow circular sandlot, pond or ice disk, overhead.  It's 1/4 the surface area of a sphere of same radius, and volume is not constrained by that radius.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DusanC on 12/10/2016 10:19 PM
IMHO inflatable half cylindrical structures are better, something like bubble insulated greenhouses:

(http://www.solarbubblebuild.com/bubble_greenhouse_test_cell/img/test_cell.jpg)

Upsides:
1. Lower mass/usable surface ratio- I emphasize this as domes have large unused volume above, if you want to use it you have to make additional construction and you block sunlight;
2. Easier construction;
3. You can make segments easier so that damage in one segment doesn't depressurize everything;
4. Easier to expand;

Active bubble foam insulation between double outer wall is a great way to manage temperature, it works like this:

(http://www.solaripedia.com/images/large/2413.gif)
NOTE: Pictures above are just to show the idea of active bubble insulation, pictures from the web, not real Mars module design.

IMHO large number of standardized inflatable modules with active bubble insulation will be the way to go.
They will be built over and under ice as it would be easy to melt ice and make tunnels in it for under ice sleeping quarters that would be filled with these segments. Segments on ice would be half way immersed in it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/15/2016 11:42 AM
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume)...

For omnidirectional radiation, yes.  As in a tall tower, or in transit. 

Not the case at ground level of course, where the radiation of interest is directed downward.  In a circular surface plan, depression or excavated column, the optimal shape for shielding is a horizontal circle:  e.g., a shallow circular sandlot, pond or ice disk, overhead.  It's 1/4 the surface area of a sphere of same radius, and volume is not constrained by that radius.

I would say the optimal pressure vessel defines the shape of the habitat (i.e. sphere or cylinder), then it is scaled up to a size where line of sights are sufficiently long and shielding becomes a relatively minor issue.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/17/2016 10:54 PM
As we've concluded many times in this thread, boring tunnels is and are actually the obvious solution for the second stage of living on Mars (the first stage being living in the lander and pre-fabricated modules). Preferably there would also be an ISS-style cupola on the surface for those rare moments when the crew has a few minutes of free time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/17/2016 11:21 PM
Tunnel boring machines on Mars to create mostly underground cities.

Hyperloops to connect the Martian cities.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/17/2016 11:24 PM
As we've concluded many times in this thread, boring tunnels is and are actually the obvious solution for the second stage of living on Mars (the first stage being living in the lander and pre-fabricated modules). Preferably there would also be an ISS-style cupola on the surface for those rare moments when the crew has a few minutes of free time.
Nah, that's not what Musk envisions. He wants people to live in the glass domes with tunnels for industrial areas. It's what he's said in the past, and it is a lot more attractive, as long as you're not paranoid about radiation. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/18/2016 04:18 AM
Also for large spaces, TBMs might not be the right solution.

I was highly impressed by that salt mine shown upthread, and it might be a lot easier to mine such spaces using more conventional mining machines, or maybe even pressurized water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/18/2016 05:06 AM

Tunneling is essential for something like Hyperloop to work out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/18/2016 05:57 AM
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 12/18/2016 12:27 PM
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

A classic case of architect failing to understand that people are in fact expected to live in the buildings he designs.

Who would've thought that people would need to install the usual rectangular cupboards, beds, sofas, shelves, bathtubs in their homes? That rectangular window panes are far easier to come by than pentagonal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/18/2016 01:10 PM
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.

Passenger comfort at such high speeds dictates straight tracks and the tracks will connect city centers respectively densely populated areas. Both will lead to lots of tunneling. Which isn't too bad though with a vactrain because the tunnel diameter can be smaller than with normal trains.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/18/2016 01:19 PM
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

A classic case of architect failing to understand that people are in fact expected to live in the buildings he designs.

Who would've thought that people would need to install the usual rectangular cupboards, beds, sofas, shelves, bathtubs in their homes? That rectangular window panes are far easier to come by than pentagonal?
Quite true. This is why domes work okay if very large but are terrible if they're small. The "edge effect" of trying to fit rectangular shapes inside a circular cross section (or the 3D analogues of each) becomes less problematic for large domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/18/2016 01:20 PM
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/18/2016 04:18 PM
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.

The only upfront convenience I can see is that a tunnel would mitigate dust issues.  Otherwise, it is possible that Mars would offer less atmospheric pressure than the earthbound hyperloop tunnels will have.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/18/2016 07:45 PM
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.

The only upfront convenience I can see is that a tunnel would mitigate dust issues.  Otherwise, it is possible that Mars would offer less atmospheric pressure than the earthbound hyperloop tunnels will have.
The biggest advantage of underground is thermal stability....

But hey - it'll be a while before you need rapid mass transport between Martian cities, something that rovers can't do...



Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/18/2016 07:53 PM
Passenger comfort at such high speeds dictates straight tracks and the tracks will connect city centers respectively densely populated areas. Both will lead to lots of tunneling. Which isn't too bad though with a vactrain because the tunnel diameter can be smaller than with normal trains.
Even if you disagree with Musk, this is a spaceX forum and he has clearly stated industry underground and living on the surface. From context Im not clear he did not just mean parks, rather than actually sleeping there, but obviously this makes it reasonable to have the place where you dock the hyperloop to visit another city on the surface.

Besides, there would be an acceleration and deceleration phase. If you had a hyperloop to something hundreds of kilometers away and your city was primarily underground, very little of the loop would have to be underground. A tiny fraction compared to the mined out volume of the city itself.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/18/2016 11:49 PM
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.

Musk is all about creating disruption in established markets and economies. His method is always to rethink things to bring down the cost of a  given product/service drastically. What if he has an idea that would bring down the cost of tunnelling to a tenth or a twentyfifth of the present costs? Cheap tunnelling looks very attractive in the many areas of the world where the surface is already overdeveloped. An L.A. to S.F. hyperloop buried the whole way would avoid a lot of expropriation and land use costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/19/2016 12:50 AM
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.
The only upfront convenience I can see is that a tunnel would mitigate dust issues.

Even then you only need a light-weight cover on an overland track. (Much much lighter than the lining for an excavated tunnel.)

But a hyperloop-type vehicle shouldn't experience dust issues. It doesn't ride on the "tracks" except for a short stretch at beginning and end (which can be easily maintained or covered). A thin layer of dust won't effect the levitation ability of the vehicle, and any over-pressure ground-effect system will (conveniently) blow away dust as the vehicle passes, so it won't accumulate. (Unlike on Earth, you can't get large movement of sand/dust in a single storm. The Martian atmosphere just physically doesn't have the carrying capacity.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/19/2016 04:27 PM
I don't understand the proposal - are you taking about a tube-less hyperloop?  That's impossible....
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/19/2016 04:52 PM
With the very low atmospheric pressure on Mars, hyperloop technology is not needed. Just build a maglev train, monorail, etc.

Tunneling is a very slow and difficult process. The machines are extremely large. First build on the surface, then when the base has the industrial capacity to build the main structure of the tunneling machine, send the harder to build parts from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/19/2016 06:11 PM
I'd add that maintenance/emergency access would be easier on an outside track.  More so if the tunnel is the cause of the issue.

Edit:  some clarity needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/19/2016 06:44 PM
With the very low atmospheric pressure on Mars, hyperloop technology is not needed. Just build a maglev train, monorail, etc.

Tunneling is a very slow and difficult process. The machines are extremely large. First build on the surface, then when the base has the industrial capacity to build the main structure of the tunneling machine, send the harder to build parts from Earth.
I thought the ram compression of the Mars atmosphere might make for a nice little air cushion system? Hyperloop operates at 1 millibar https://en.wikipedia.org/wiki/Hyperloop
and Mars atmospheric pressure is 6 millibar https://en.wikipedia.org/wiki/Atmosphere_of_Mars

It might save construction costs on the un-accelerated parts of the tracks and be used for propulsion?  Don't really need to worry about noise on Mars.
Don't see any point in tunneling for a Mars hyperloop at least for a few centuries.  But if we have underground cave habitats, then perhaps underground stations as well.

If Mars lighting under a dome is insufficient to grow plants in an intensive way, and if dome constructions costs are too high, might we just make very large solar arrays and grow everything underground?  After all, agriculture is also an industrial process, in a way, so we would not be going against a Musk quote.  A true food production dome is probably not a very comfortable environment, as anyone who has visited a green house will tell you.  Too humid and too bright.
After all the least effective part of a greenhouse with electric lighting will be the photosynthesis.  We might use the power losses in the power system to heat the colony.  Does photosynthesis scale linearly with lighting levels?

Lots of questions still, before we can design the habitat....
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/19/2016 06:58 PM
We haven't talked much about getting about in the habitat, in particular once it reaches more than a few thousand people.  Will walking be the only option?  How about vacuum tube transportation systems for small to mid size items?  These are notoriously unreliable on Earth, but might make sense on Mars, where there is ample supply of near vacuum.

If we go for an hyperloop for long distance, and we base our designs on the capacity of SpaceX, can we expect anything else than self driving people movers for all the larger distance, than combine up into an hyperloop vehicle as per this Dubai concept?

https://www.youtube.com/watch?v=fze5spdN3nU

Of course, exercise is good for you, perhaps in particular at 1/3g.  So people movers might be actively discouraged.

And what about air treatment?  Should this be centralized or distributed? And water?  Distributed seems safer, but usually large central plants are more efficient.

On the third hand, as the Moties would say, transportation is not really free, and youmight have a gain in promoting local usage.  Composting toilets, rather than our slightly mad water based system of today?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/19/2016 08:43 PM
(snip)
... But if we have underground cave habitats, then perhaps underground stations as well.

If Mars lighting under a dome is insufficient to grow plants in an intensive way, and if dome constructions costs are too high, might we just make very large solar arrays and grow everything underground?  After all, agriculture is also an industrial process, in a way, so we would not be going against a Musk quote.  A true food production dome is probably not a very comfortable environment, as anyone who has visited a green house will tell you.  Too humid and too bright.
After all the least effective part of a greenhouse with electric lighting will be the photosynthesis.  We might use the power losses in the power system to heat the colony.  Does photosynthesis scale linearly with lighting levels?

Lots of questions still, before we can design the habitat....

I agree with the insight about fields of solar panels and industrial "greenhouses" in caves and tunnels below. I think solar panels will be a better use of the surface than real greenhouses. Nuclear and solar, with fuel cell backup can share the power production responsibility. The LED-lit greenhouse caves with optimized wavelengths and optimized virtual day & night lengths etc. will then draw power from the grid. More efficient, more reliable and having flexibility with the sources & uses of power is always good for plan b's and plan c's.

If we expand the vision of caves under fields of solar panels to imagine what else is possible, I think that the imaginative use of multi-level landscapes will turn out to be important in the urban planning of amazing cities on Mars.

Landscapes filled with canyons, craters and mesas expose multiple horizontal and vertical surfaces. Multi-level landscapes make it easier to design an underground city that is not completely underground. Parts of caves can be exposed as domes on the south face of a crater wall, mesa or canyon, and parts of underground tunnels can be exposed and covered with geodesic structure & glass, mixing the indoor and outdoor experience as people move about the city. This way, people can spend most of a Sol in a fully underground zero radiation environment yet still have on-tap, frequent access to the exposed domes and exposed tunnels for eyeball contact with open vistas, the horizon, the great outdoors, the sun and wind, the dust devils, the human activity on the valley floor and the red or blue skies. I think the best uses of exposed domes will be public places for green parks, socializing and leisure, places of creative work, places of living (except sleeping) and the best uses of exposed tunnels would be to make walking or biking between points more interesting and uplifting. Caves and underground large tunnels would be best for industry, the radiation-safe portion of sleeping and living quarters, greenhouses and so forth.

Also, with multiple levels and a semi-underground city excavated in-between, things that should be above the city can be above it, such as the solar panel fields up top kept out of dust and shadow, or even landing pads, with easy vertical access down to the city, and things that should be below the city can be below, like the canyon floor that might be scoured for water- and mineral- bearing regolith, probably creating a regular local dust cloud in the process.

Finally, such landscapes also create natural protective divisions between areas, making it easier to zone nearby landing pads or nuclear power.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RanulfC on 12/21/2016 09:07 PM
On the third hand, as the Moties would say, transportation is not really free, and youmight have a gain in promoting local usage.

The correct terminology is "Gripping Hand" just FYI :)

Randy
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/22/2016 07:41 AM
I envision a clear, one piece dome sited on top of a vertical, cylindrical shaft descending 5 or 6 levels down.  Each level has a terrace extending slightly further into the shaft than the one above until the lowest level is actually the shaft floor.  On the terraces are gardens, cafe, park and other common areas.  Radiating away from the shaft on each level are tunnels containing living and working areas, storage, utilities, medical, education etc.

The bigger the dome, the larger the terraces or the more numerous the levels.  Four horizontal tunnels per level spaced 90 degrees apart would be major thoroughfares with other areas/hallways branching off them.

Tunnels on level one would be at 12, 3, 6 & 9 o'clock.  Level two at 1, 4, 7 & 10 o'clock etc so that there is a vertical offset of 3 levels between the major spokes that would allow them to be joined by ramps for wheeled traffic at a suitable distance from the shaft.  Stairways and elevators could be put just about anywhere.

Smaller observation domes and airlocks would be at the far end of each spoke on level one.

How big a dome could that BFS carry ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 12/22/2016 07:14 PM
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/23/2016 07:13 AM
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!
I have wondered whether you could inflate a sphere and then have a robotic sprayer in the center that slowly builds up layer after layer of a clear surface.

That does not sound very strong but suppose the sprayer had two parts: a fibre that it lays out in geodesics and a plastic of the exact same optical properties. The robotic sprayer could monitor the surface with incredible accuracy by laser interference.

This is just science fiction at the moment, but I can see that sort of technology progressing very rapidly. Once you get past the fact it is impossible it could become easy ;)

Even the inflatable part may seem incredibly naive in a decade or so. We may just print the thing.

Two interesting things to google:
* 3d printing polycarbonate
* 3d printing pen :)

It is amazing how this stuff is moving along and even becoming commonplace.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/23/2016 07:31 AM
There's a story doing the rounds about an "igloo" concept for a 4-person Mars habitat called "Ice Home", coming out of NASA's Langley Research Center. (As distinct from the earlier "Ice House (http://payload409.cargocollective.com/1/12/384722/10487141/Mars-Ice-House_section_lr_1000.jpg)" concept that won the design challenge.)

[edit: It looks like the concept comes from many of the same people who developed the Ice House proposal. Space Exploration Architecture and Clouds Architecture Office, working with Langley.]

Space.com article (http://www.space.com/35101-mars-ice-home-design.html)

Daily-Fail article (http://www.dailymail.co.uk/sciencetech/article-4057680/The-ice-homes-Mars-Incredible-designs-reveal-frozen-habitats-one-day-call-home.html)

(Can't find anything at nasa.gov.)

Essentially it's a semi-transparent multi-layered inflatable habitat. A dome-like outer layer covers a toroidal pressurised habitat. The space between the toroidal hab and the outer dome is filled with ISRU-water and allowed to freeze. Between the skin of the toroidal hab and the ice is a pillow-like (or bubblewrap-like) layer which is pressurised with ISRU- CO2, which provides a cheap insulating air-gap between the hab and the outer dome.

(There might also be a liquid water layer between the CO2-bubblewrap and the habitat skin. Or I'm misreading the labels.)

Unlike many Mars hab concepts (for example (https://www.thesun.co.uk/wp-content/uploads/2016/11/nintchdbpict000281222478.jpg?w=960&strip=all)), they at least understand about pressure.

Some images:

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D31100000578-4057680-The_translucent_ice_layer_around_the_outside_of_the_pod_would_en-a-43_1482400185696.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D31100000578-4057680-The_translucent_ice_layer_around_the_outside_of_the_pod_would_en-a-43_1482400185696.jpg)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg)

(http://www.space.com/images/i/000/061/091/original/icehouse-4-inside.jpg?1482267946?interpolation=lanczos-none&downsize=*:1400) (http://www.space.com/images/i/000/061/091/original/icehouse-4-inside.jpg?1482267946?interpolation=lanczos-none&downsize=*:1400)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg)


The use of space is... odd. Tiny machine-room, even smaller greenhouse. Huge ward-room, "Library", "Study", etc. But that's fairly typical of these kinds of proposals.

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2F900000578-4057680-The_pods_would_include_areas_for_work_sleep_recreation_food_prep-a-30_1482399958004.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2F900000578-4057680-The_pods_would_include_areas_for_work_sleep_recreation_food_prep-a-30_1482399958004.jpg)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2FD00000578-4057680-The_idea_is_that_the_Ice_Home_will_form_just_one_component_of_a_-a-37_1482399958155.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2FD00000578-4057680-The_idea_is_that_the_Ice_Home_will_form_just_one_component_of_a_-a-37_1482399958155.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/23/2016 07:46 AM
I have wondered whether you could inflate a sphere and then have a robotic sprayer in the center that slowly builds up layer after layer of a clear surface.

That was the idea behind the original "Ice House" 3d-printed concept.

(http://payload428.cargocollective.com/1/12/395831/10866388/19_Mars-Ice-House_deploy-bots-inner_07_670.jpg) (http://payload428.cargocollective.com/1/12/395831/10866388/19_Mars-Ice-House_deploy-bots-inner_07_670.jpg)

(http://www.rhinecapital.com/investmentinsights/wp-content/uploads/2015/10/Mars-Ice-House-Yard.jpg) (http://www.rhinecapital.com/investmentinsights/wp-content/uploads/2015/10/Mars-Ice-House-Yard.jpg)

http://greenbuildingelements.com/wp-content/uploads/2015/10/Ice-House-3.jpg (http://greenbuildingelements.com/wp-content/uploads/2015/10/Ice-House-3.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/24/2016 09:31 AM
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/24/2016 12:09 PM
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.

Ah, but I do!  So if you all want to flesh out the idea a little more, i'll be glad to give it a try!

But I agree we need a bigger dome for this to be an interesting habitat.  How large could an assembled dome be?  Let's suppose it gets held down by the mass of those terraces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/25/2016 10:56 AM
If, as KelvinZero mentioned above, we could 3D print polycarbonate and a reasonable size dome could be made on site then let's pick a size to start with. Say 30 mt diameter.  Level one terrace extends 3 mt all around leaving 24 mt open.  Level two extends in another 4 mt leaving 16 mt and level three goes 5 mt leaving a 6 mt diameter floor in the center of level four order the dome.  The idea being that the higher the terrace, the more light it will receive therefore it needs less area under the dome.  Lower terraces are larger to capture more of the reduced light, if you get my drift.

Conversely if all terraces are set at 3 mt then you can have 5 levels under the same 30 mt dome.

Mick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/25/2016 01:25 PM
You don't want to 3D print it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/25/2016 02:51 PM
If, as KelvinZero mentioned above, we could 3D print polycarbonate and a reasonable size dome could be made on site then let's pick a size to start with. Say 30 mt diameter.
To be clear I was not advocating any specific technology I am aware of today, such as existing polycarbonate 3d printing methods, just saying things are moving rapidly so schemes like relying on an inflated sphere to dictate your shape might seem very naive in the future.

3d printing might imply "building up dot by dot" also. My layman's guess is that if we went from a feedstock to a dome it would be more like cloth from spiderwebs than Minecraft. Just a guess though.

I think large monolithic clear domes is a worthwhile subtopic. Maybe other people can think of entirely different approaches to achieving this.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 12/25/2016 03:28 PM
Where would you get the polycarbonate feed stock from?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/25/2016 03:43 PM
Where would you get the polycarbonate feed stock from?

From Earth, of course. The feedstock would be very compact compared to the finished dome, so it and the printer system would easily fit in a BFS.

Once a colony is established, polycarbonate can be produced on Mars, but it's not going to be as easy to do as people think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/25/2016 04:44 PM
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/25/2016 05:18 PM
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.

Good point. Use the right tool for the job.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/25/2016 08:02 PM
OK.  I'm cool with a sectional dome. In this case it is primarily there to let in light and hold in air, not to provide living area.  I don't want to get into the geodesic discussion again.  Is there some other method of on site fabrication that could be used ?  What about spiral wrap off a roll and laser fuse the joints and cap it with a one piece section at the top ?

Mick
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/26/2016 03:22 AM
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.
I think you have some specific current day 3d printing technology in mind. Im not arguing anything to replace current payloads, or even Elon Musk's concept of assembling pressure tight geodesic domes from faces, though that is also not a space-ready technology as far as I know.

If we are discussing "What technology are we confident with today" then sure, this is ruled out. If we are discussing how to produce a monolithic dome with no crisscross of seams interfering with the view, then assembly from parts may be ruled out. They are different but valid things to discuss.

I think producing a dome from feedstock in one monolithic piece has the potential to be:
* stronger, due to no joins.
* not horribly slow, because one spraying machine can build up the entire surface in sweeps.
* Potentially easier to assemble robotically, so the time to assemble may matter less
* Perfectly transparent (because we are not talking of any specific technology. Also it would not be too hard to add a polishing phase)
* a more pleasing final result, without the cage of seams.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/26/2016 07:03 AM
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.

Ah, but I do!  So if you all want to flesh out the idea a little more, i'll be glad to give it a try!

But I agree we need a bigger dome for this to be an interesting habitat.  How large could an assembled dome be?  Let's suppose it gets held down by the mass of those terraces.

It is also possible to have a completely spherical dome, half-buried, with the underground stepped terraces integrated into the bottom half.

Alternatively, the spherical dome can be half-buried vertically into a natural vertical wall (e.g. mesa, canyon) with the stepped terraces arranged like theatre stalls so that they all have panoramic views of the outdoors.

The dome would therefore divide the terraces at all levels into two parts, one inside the dome and one outside.

Interesting (and I think on the whole beneficial) form and function consequences would follow...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:16 AM
I know this thread is called "Envisioning Amazing Martian Habitats" but I still think that all these dome concepts and ideas are only valid for the far-off future. The early Mars years will be about survival and gaining a fooothold rather than grandeur. Pre-fab habitats and tunnels more than domes and ice sculptures.

Why domes? - To get light it is much easier to deploy solar panels and indoor lighting. For the view? - An ISS-style cupola should suffice. On the ISS they are more than happy to have the cupola for the few moments they can steal away from essential work. It has an ever-changing view unlike a Martian cupola where I can well imagine that the arid views will get old after a while.

Tunnelling provides radiation protection, provides a pressurized interior and provides an expansion potential only limited by the excavation equipment. The "building material" is already there: removing it is the issue, not bringing it from Earth.

A tunneling machine which can also solidify the walls is really the way forward for the early post-pre-fab period. A single machine that can be repaired with 3D printed parts. It would provide a habitat expanding in size daily, with exactly the ground plan needed, free of specific pressure vessel shape limitations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: paolopaolo on 12/26/2016 09:28 AM
right, and probably is not necessary to dig tunnels. There may be lava tunnel that would be perfect. Just a note: I believe that the views of Mars will be wonderful
http://www.lpi.usra.edu/decadal/leag/AndrewWDagaFINAL.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 11:48 AM
Alternatively, the spherical dome can be half-buried vertically into a natural vertical wall (e.g. mesa, canyon) with the stepped terraces arranged like theatre stalls so that they all have panoramic views of the outdoors.

If you are building against a linear wall, I wouldn't use a spherical structure, but a cylindrical one. (Rounded ends, obviously.) It allows more natural expansion, instead of having to demolish and rebuild the dome every time you want to expand, you just add another identical section to the end to lengthen it. The old end-caps become the safety barriers between sections.

right, and probably is not necessary to dig tunnels. There may be lava tunnel that would be perfect.

As the article notes, the problem is that the best lava tubes probably don't correlate with the best sites for other features like water.

(The ideal would be a lava tube that has collected water (and other volatiles) from prior warm periods, obviously. But it's unlikely to be an early find.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 11:50 AM
that can be repaired with 3D printed parts.

We shouldn't assume that 3d-printing (or nano-tech, or bio-tech) will develop to that level. The risk is that you end up using it as "handwavium" to solve any problem. Technology as magic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 11:51 AM
I agree that lava tubes are exciting and have the promise of huge interior spaces. But there are also many problems. You can't choose your location freely. If you dig your own tunnels you can place them optimally in close proximity to resources.

The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 12:08 PM
The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

It would be exactly the same as assessing a site for drilling (except that you have access to inside the rock.)

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Can't see the logic of that. If you are comparing with tunnelling out the entire habitat, you can surely drill a short accessway to the main lava tunnel wherever it's convenient for you.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.

There are holes into lava tubes that are hundreds of metres across. Some rill features are over a kilometre across and thousands of kilometres long.

Space is not going to be an issue.

As for "compartmentalising", you still need to build your actual habitat inside the lava tube. I doubt you would simply pressurise the raw tunnel. (Likewise for excavated tunnels, you are going to line the walls.)

--

IMO, the only issue with lava tunnels is that you don't get to choose the site. But that also holds true, if to a lesser extent, with excavated tunnels. The ideal site to drill is likely not to be ice-rich. (Unless you are living under the ice, as KelvinZero proposes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/26/2016 12:15 PM
Tunnelling provides radiation protection, provides a pressurized interior and provides an expansion potential only limited by the excavation equipment. The "building material" is already there: removing it is the issue, not bringing it from Earth.

You need lots of concrete and steel to build a tunnel. At least on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 01:24 PM
You need lots of concrete and steel to build a tunnel. At least on Earth.

Not when you drill in bedrock. For rock of lesser density it could be possible to vitrify the tunnel sides and ceilings in lieu of lining. If they would want to tunnel through sand on Mars (I wouldn't know why) they could build brick arches made from the excavated material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 07:44 PM
You need lots of concrete and steel to build a tunnel. At least on Earth.

Not when you drill in bedrock. For rock of lesser density, it could be possible to vitrify the tunnel sides and ceilings in lieu of lining. If they would want to tunnel through the sand on Mars (I wouldn't know why) they could build brick arches made from the excavated material.
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight. Plus digging through the loose material is much easier than drilling excavating a tunnel in hard rock. The microwave option would make the excavation slower but would not require materials to be created to create the walls since the materials in place are used. Thus a digging machine vs a drilling machine would be an easier first "subterranean" emplacement of living and workspace for the colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/26/2016 07:50 PM
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight.

I keep hearing that. I do wonder, if it is that easy why is it not used on earth?
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 07:57 PM
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight.

I keep hearing that. I do wonder, if it is that easy why is it not used on earth?
Requires extreme low humidity and air pressure (near vacuum). Otherwise, the microwaves heat the moisture and atmosphere keeping the material from reaching the very high internal temperatures to cause fusing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:34 PM
Yes, it should be the perfect process for the Martian atmosphere. OldAtlasEGuy, do you have any good links that go deeper into the method? - My knowledge of it is pretty superficial (no pun intended).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:49 PM
The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

It would be exactly the same as assessing a site for drilling (except that you have access to inside the rock.)

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Can't see the logic of that. If you are comparing with tunnelling out the entire habitat, you can surely drill a short accessway to the main lava tunnel wherever it's convenient for you.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.

There are holes into lava tubes that are hundreds of metres across. Some rill features are over a kilometre across and thousands of kilometres long.

Space is not going to be an issue.

As for "compartmentalising", you still need to build your actual habitat inside the lava tube. I doubt you would simply pressurise the raw tunnel. (Likewise for excavated tunnels, you are going to line the walls.)

--

IMO, the only issue with lava tunnels is that you don't get to choose the site. But that also holds true, if to a lesser extent, with excavated tunnels. The ideal site to drill is likely not to be ice-rich. (Unless you are living under the ice, as KelvinZero proposes.)

Paul, wouldn't a team actually drilling through rock get a better knowledge of it than a team which is just exploring a lava tube? To my mind, in the first case the drilling team will get more info about possible hidden features in the rock.

Regarding drilling a short access-way to an already existing lava tube. Well, if you will need to bring drilling equipment along in any case when you aim to exploit a lava tube... - Doesn't that negate much of the advantage of using an already existing tube? I agree that lava tubes will most probably require drilling to be useful. So, the drilling equipment needs to go to Mars in any case.

My hope is that the drilled tunnels would indeed in themselves be the habitat. Without any separate habitat built inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 08:50 PM
Yes, it should be the perfect process for the Martian atmosphere. OldAtlasGuy, do you have any good links that go deeper into the method? - My knowledge of it is pretty superficial (no pun intended).
http://www.techbriefs.com/component/content/article/ntb/tech-briefs/physical-sciences/16856 (http://www.techbriefs.com/component/content/article/ntb/tech-briefs/physical-sciences/16856)

It only addresses Lunar regolith but should be applicable Mars regolith with adjustments based on the regolith makeup.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 09:07 PM
Ah yes, I remember reading about that study. Thanks for the link! Would be really cool to have a rover going to Mars to microwave various soil types and see how their properties could be changed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 09:40 PM
Ah yes, I remember reading about that study. Thanks for the link! Would be really cool to have a rover going to Mars to microwave various soil types and see how their properties could be changed.
For the test the study only used a 60W microwave. So with losses a systems that uses ~200W or less should be able to test assumptions with real Mars regolith. In some ways having Lunar regolith brought back has made things easier for the Lunar regolith investigations.

The study basics was that it is a usable capability but will require adjustment based on the actual makeup of the material being sintered (made into a block).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 10:56 PM
wouldn't a team actually drilling through rock get a better knowledge of it than a team which is just exploring a lava tube? To my mind, in the first case the drilling team will get more info about possible hidden features in the rock.

By then you are already committed to the site.

My point was that surveying candidate lava tubes is not going to be more difficult than surveying potential tunnelling sites before you start tunnelling.

Regarding drilling a short access-way to an already existing lava tube. Well, if you will need to bring drilling equipment along in any case when you aim to exploit a lava tube... - Doesn't that negate much of the advantage of using an already existing tube?

Do you feel that building a door into an existing wall requires as much equipment and supplies as building an entire house?

Also digging down with an opening above (or digging a ramp) is easier than digging horizontally underground. And for horizontal tunnelling, it's necessary before the TBM can start operating anyway. TBM's can't self-insert, can't dig down. So you need to bring the entirely separate "entry digging" equipment in order to deploy your horizontal tunnelling machine. A lava tube only needs the "entry digging" equipment and can skip the giant, heavy, high-maintenance TBM.

Additionally, digging an accessway into a lava-tube is going to be a hell of lot quicker than tunnelling the entire habitat volume. It means you can get established much quicker, which then allows you to turn that manpower, electrical power, supplies and equipment to other tasks, like ISRU "mining".

(There are lava-tubes with existing openings, of course, but I'm assuming the ideal site will end up being a sealed section.)

My hope is that the drilled tunnels would indeed in themselves be the habitat. Without any separate habitat built inside.

I'm not aware of any modern heavily-used tunnel on Earth which isn't lined/cased. Casing is usually built into the horizontal tunnelling process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/27/2016 07:31 AM
TBM's are too restricted in their range of movement.  Great for straight or slightly curved circular tunnels.  Use a Roadheader.  Excavates a relatively flat floor and can change direction easily and quickly.  Can be used to dig from scratch or to enter caves, lava tubes etc.

Mick
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/27/2016 01:07 PM
TBM's are too restricted in their range of movement.  Great for straight or slightly curved circular tunnels.  Use a Roadheader.

I was using "TBM" in the most generic sense of any dedicated tunnelling machine.

However, AIUI, roadheaders are also limited in how much they can dig down. If you are cutting into the side of a crater or hill-face, say, they would work fine. But when you were starting from relatively level ground and need to cut down to the level of the tunnel, you need to use other means to cut a ramp and start them off with an appropriate cutting-face. (Say hydraulic breaker/hammer.) And the method you use to create the starting surface for the roadheader is the entirety of gaining entry to a lava tube. Which was my point.

[Hydraulic breakers are modular and can attach to a suitable backhoe or loader, which can then be used for scraping the debris. Multi-purpose machines seem more likely than single purpose ones. You are going to bring some kind of backhoe/bucket-loader machine anyway, you might as well bring a rock-breaking module for it.]

--

OTOH, if the method of extracting water requires conventional mining techniques, then the sheer amount of mining required will mean a surfeit of equipment of all types will be available for comparatively trivial tasks like digging out a habitat.

--

OTGH, even if you require exactly the same equipment for the two jobs (cutting an entry-way into a lava-tube vs digging habitat tunnel(s) from scratch) you will still be finished digging into a lava-tube before the hab-tunnel project has dug its first room. Hence the equipment is freed up to go back to mining work much much earlier.

Of course, that assumes a lava-tube is available near a source of water. Which, IMO, is the only real problem with lava-tubes. They aren't going to be where you need them to be.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/27/2016 01:38 PM
Let's don't forget cut and cover tunneling. Dig a ditch, build structure in ditch, and cover it up. Walls can be microwave fused or cylindrical structures can be placed in the ditch. No TBM required.

What happened to "amazing" habitats? This has turned into a construction technique discussion as opposed to architecture. In other words, let's talk more about what to do with tunnels instead of how to build them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/27/2016 04:51 PM
Let's don't forget cut and cover tunneling. Dig a ditch, build structure in ditch, and cover it up. Walls can be microwave fused or cylindrical structures can be placed in the ditch. No TBM required.

What happened to "amazing" habitats? This has turned into a construction technique discussion as opposed to architecture. In other words, let's talk more about what to do with tunnels instead of how to build them.

Actually the OP solicited ideas for amazing habitats and also asked what tools or supplies you would want to take to Mars to build them. To keep things real, as much as possible:

Quote
What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?

So discussion of methods that enable the construction of amazing habitats is on topic. Very interesting nuggets emerge from such discussions, like the suggestion upthread that fusing freshly carved rock with microwaves will be well suited to excavating underground habitats on Mars because of the low atmospheric pressure and humidity there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/27/2016 08:44 PM
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement

Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.

These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize. Once a section is pressurized, the airlock is used to transport the excess material dug from the tunnel in airtight containers out back through the tunnel. The tunneling machine makes the containers as well but the carriage/wheels are reused and not made by the tunnel machine. Remember these machines only move centimeters per hour.

But at only 5 cm in 1 hour will make a structurally complete 30m of tunnel per month and 360m of tunnel in 1 Earth year. If the tunnel is 15m in diameter with 4 floors that adds ~40m^2 per 1m length of floor space, that is in 1 Earth year 14,400 m^2 of floor space. NOTE in an gravity field the primary concern is on floor space for living area. But for packed storage the concern is volume. In volume it is 63,000m^3. If each person is assigned 100m^2 for living space and an additional storage and common area space of 100m^2 per person then the one year of tunneling would provide space for 72 additional colonists. It would take only 10 tunneling machines to keep up with 1000 colonists arriving every synod.

A 30m diameter tunneling machine would produce at the 5cm/hr crawl rate, space for 800 colonists per tunneling machine per synod. 13 machines would provide room for 10,000 new colonists per synod. That is at 250 colonists per ITS, 40 ITS filled with colonists per synod.

Remember the power used is related to crawl speed. At these low craw speeds the power usage is moderate. With moderate power usage the heat rejection can be handled by moderate cooling and the heating of the excess regolith up to room temp so as it is transported through the pressurized tunnel back out of the habitat it does not cause problems. In the 15m diameter tunnel machine case, 9 (3mX2mx3m) containers of regolith is transported through the airlock and back down the tunnel every day. One container size of material is used for internal structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/28/2016 12:11 AM
Radial and dome.  30m dome, 6m tunnel, 3m terrasses.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Terra Incognita on 12/28/2016 11:14 AM
That's a nice one Lamontagne.

The two things that strike me about that structure is that you could include an outer circular tunnel linking all of the other tunnels. That would be important in the event of a dome pressure failure so that the tunnels weren't dependent on the dome as the only link to the other tunnels.

The second thing is that it is infinitely expandable only limited by terrain. You can repeat that structure again and again, all linked. You could eventually tunnel a tube network below it. As you improve your dome technology you can have a larger and larger domes.

It looks like a very practical structure that can be scaled as skills and technology improve.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 02:35 PM
MickQ,

I was puzzled by the radial tunnels in the description. Looking at the Lamontagne's rendering (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1623589#msg1623589), I'm even more confused.

What's the point in having so many separate tunnels?

Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

(http://www.penninetaichi.co.uk/index_files/image10511.jpg) (http://www.penninetaichi.co.uk/index_files/image10511.jpg)

[Lamontagne, if that's a road-header inside your tunnel, then your tunnels should be hemi-cylindrical. Flat-floored half-pipes.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/28/2016 02:56 PM
Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

If you still want to use mining equipment, angle up a ramp at the end of the tunnel and roll out on the surface. It would be a good idea to have a surface exit every so often.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

A good idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/28/2016 03:27 PM
Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

If you still want to use mining equipment, angle up a ramp at the end of the tunnel and roll out on the surface. It would be a good idea to have a surface exit every so often.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

A good idea.

If trenching displaces a lot more material than the tunnel, then trenching may be more expensive.  I don't know where the cut off depth is for economical trenching vs digging.
I've proposed the spiral twice before ;-)   It never gets much enthusiasm, somehow.

The domed pit might be done as a Guggenheim museum spiral ramp.  Otherwise some hard rock mines have spiraling access tunnels.  The Guggenheim would be more elegant and create a nice central space.

Next iteration will have flat tunnel floors, if there is enough enthusiasm for a particular design.
It would be interesting to have a surface sintering machine.  I guess we might have a few tens of kW to work with, since we will be needing the power later for the habitat anyway.  The sintering would stabilize the rock wall and prevent leaks and spalling. The rock may have a certain amount of void space, specially if it is sandstone, so the sintering might include a densification of the material?

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 03:58 PM
I thought the giant open space with pillars left on a square grid was much more suitable for all purposes.

Tunnels are for transport.  They are 1D.  You want a 2D floor space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 07:44 PM
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement
Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.
These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize.

Once again, we shouldn't treat 3d-printing as magic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/28/2016 08:45 PM
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement

Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.

These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize. Once a section is pressurized, the airlock is used to transport the excess material dug from the tunnel in airtight containers out back through the tunnel. The tunneling machine makes the containers as well but the carriage/wheels are reused and not made by the tunnel machine. Remember these machines only move centimeters per hour.

But at only 5 cm in 1 hour will make a structurally complete 30m of tunnel per month and 360m of tunnel in 1 Earth year. If the tunnel is 15m in diameter with 4 floors that adds ~40m^2 per 1m length of floor space, that is in 1 Earth year 14,400 m^2 of floor space. NOTE in an gravity field the primary concern is on floor space for living area. But for packed storage the concern is volume. In volume it is 63,000m^3. If each person is assigned 100m^2 for living space and an additional storage and common area space of 100m^2 per person then the one year of tunneling would provide space for 72 additional colonists. It would take only 10 tunneling machines to keep up with 1000 colonists arriving every synod.

A 30m diameter tunneling machine would produce at the 5cm/hr crawl rate, space for 800 colonists per tunneling machine per synod. 13 machines would provide room for 10,000 new colonists per synod. That is at 250 colonists per ITS, 40 ITS filled with colonists per synod.

Remember the power used is related to crawl speed. At these low craw speeds the power usage is moderate. With moderate power usage the heat rejection can be handled by moderate cooling and the heating of the excess regolith up to room temp so as it is transported through the pressurized tunnel back out of the habitat it does not cause problems. In the 15m diameter tunnel machine case, 9 (3mX2mx3m) containers of regolith is transported through the airlock and back down the tunnel every day. One container size of material is used for internal structures.

Really fascinating calculations OldAtlasEGuy. Sounds like you have experience in tunnelling? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 09:42 PM
How much does a 30 m TBM weigh?


Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

I think key to excavating is to find easy to remove soil (a salt deposit would be awesome) and create large caverns.

If the cavern is large, you need to worry a lot less about "wall finishing", which makes the process not efficient, and the TBM less suitable.

For transport, however, a 2-3 m TBM might be an efficient way to connect nearby structures to each other.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 10:13 PM
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 10:19 PM
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.
Yup, was trying to look that up.

They are optimized for the wrong type of problem - boring a straight narrow line through whatever adversity lies between points A and B.

We're looking for a nice large habitable volume, more like an underground parking garage, and place it where we choose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/29/2016 12:00 AM
Quote
Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

This has the added benefit of allowing for processing the regolith before using to bury the structures.  Nice to know exactly what is over the top of you too.

Quote
I think key to excavating i